[POWERPC] Rename device_is_compatible to of_device_is_compatible

for consistency with other Open Firmware interfaces (and Sparc).

This is just a straight replacement.

This leaves the compatibility define in place.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/drivers/serial/pmac_zilog.c b/drivers/serial/pmac_zilog.c
index cd92a39..0fa9f67 100644
--- a/drivers/serial/pmac_zilog.c
+++ b/drivers/serial/pmac_zilog.c
@@ -1450,7 +1450,7 @@
 	/*
 	 * Detect port type
 	 */
-	if (device_is_compatible(np, "cobalt"))
+	if (of_device_is_compatible(np, "cobalt"))
 		uap->flags |= PMACZILOG_FLAG_IS_INTMODEM;
 	conn = of_get_property(np, "AAPL,connector", &len);
 	if (conn && (strcmp(conn, "infrared") == 0))