tree-wide: convert open calls to remove spaces to skip_spaces() lib function

Makes use of skip_spaces() defined in lib/string.c for removing leading
spaces from strings all over the tree.

It decreases lib.a code size by 47 bytes and reuses the function tree-wide:
   text    data     bss     dec     hex filename
  64688     584     592   65864   10148 (TOTALS-BEFORE)
  64641     584     592   65817   10119 (TOTALS-AFTER)

Also, while at it, if we see (*str && isspace(*str)), we can be sure to
remove the first condition (*str) as the second one (isspace(*str)) also
evaluates to 0 whenever *str == 0, making it redundant. In other words,
"a char equals zero is never a space".

Julia Lawall tried the semantic patch (http://coccinelle.lip6.fr) below,
and found occurrences of this pattern on 3 more files:
    drivers/leds/led-class.c
    drivers/leds/ledtrig-timer.c
    drivers/video/output.c

@@
expression str;
@@

( // ignore skip_spaces cases
while (*str &&  isspace(*str)) { \(str++;\|++str;\) }
|
- *str &&
isspace(*str)
)

Signed-off-by: André Goddard Rosa <andre.goddard@gmail.com>
Cc: Julia Lawall <julia@diku.dk>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Neil Brown <neilb@suse.de>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Cc: David Howells <dhowells@redhat.com>
Cc: <linux-ext4@vger.kernel.org>
Cc: Samuel Ortiz <samuel@sortiz.org>
Cc: Patrick McHardy <kaber@trash.net>
Cc: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/pnp/interface.c b/drivers/pnp/interface.c
index c3f1c8e..68b0c04 100644
--- a/drivers/pnp/interface.c
+++ b/drivers/pnp/interface.c
@@ -310,8 +310,7 @@
 		goto done;
 	}
 
-	while (isspace(*buf))
-		++buf;
+	buf = skip_spaces(buf);
 	if (!strnicmp(buf, "disable", 7)) {
 		retval = pnp_disable_dev(dev);
 		goto done;
@@ -353,19 +352,13 @@
 		pnp_init_resources(dev);
 		mutex_lock(&pnp_res_mutex);
 		while (1) {
-			while (isspace(*buf))
-				++buf;
+			buf = skip_spaces(buf);
 			if (!strnicmp(buf, "io", 2)) {
-				buf += 2;
-				while (isspace(*buf))
-					++buf;
+				buf = skip_spaces(buf + 2);
 				start = simple_strtoul(buf, &buf, 0);
-				while (isspace(*buf))
-					++buf;
+				buf = skip_spaces(buf);
 				if (*buf == '-') {
-					buf += 1;
-					while (isspace(*buf))
-						++buf;
+					buf = skip_spaces(buf + 1);
 					end = simple_strtoul(buf, &buf, 0);
 				} else
 					end = start;
@@ -373,16 +366,11 @@
 				continue;
 			}
 			if (!strnicmp(buf, "mem", 3)) {
-				buf += 3;
-				while (isspace(*buf))
-					++buf;
+				buf = skip_spaces(buf + 3);
 				start = simple_strtoul(buf, &buf, 0);
-				while (isspace(*buf))
-					++buf;
+				buf = skip_spaces(buf);
 				if (*buf == '-') {
-					buf += 1;
-					while (isspace(*buf))
-						++buf;
+					buf = skip_spaces(buf + 1);
 					end = simple_strtoul(buf, &buf, 0);
 				} else
 					end = start;
@@ -390,17 +378,13 @@
 				continue;
 			}
 			if (!strnicmp(buf, "irq", 3)) {
-				buf += 3;
-				while (isspace(*buf))
-					++buf;
+				buf = skip_spaces(buf + 3);
 				start = simple_strtoul(buf, &buf, 0);
 				pnp_add_irq_resource(dev, start, 0);
 				continue;
 			}
 			if (!strnicmp(buf, "dma", 3)) {
-				buf += 3;
-				while (isspace(*buf))
-					++buf;
+				buf = skip_spaces(buf + 3);
 				start = simple_strtoul(buf, &buf, 0);
 				pnp_add_dma_resource(dev, start, 0);
 				continue;