kgdb: sparse fix

- Fix warning reported by sparse
kernel/kgdb.c:1502:6: warning: symbol 'kgdb_console_write' was not declared.
	Should it be static?

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
diff --git a/kernel/kgdb.c b/kernel/kgdb.c
index 79e3c90..3ec23c3 100644
--- a/kernel/kgdb.c
+++ b/kernel/kgdb.c
@@ -1499,7 +1499,8 @@
 	return 1;
 }
 
-void kgdb_console_write(struct console *co, const char *s, unsigned count)
+static void kgdb_console_write(struct console *co, const char *s,
+   unsigned count)
 {
 	unsigned long flags;