[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/arch/powerpc/platforms/powermac/low_i2c.c b/arch/powerpc/platforms/powermac/low_i2c.c
index 5430e14..3f507ab 100644
--- a/arch/powerpc/platforms/powermac/low_i2c.c
+++ b/arch/powerpc/platforms/powermac/low_i2c.c
@@ -1207,7 +1207,7 @@
 				if (strcmp(np->name, p->name))
 					continue;
 				if (p->compatible &&
-				    !device_is_compatible(np, p->compatible))
+				    !of_device_is_compatible(np, p->compatible))
 					continue;
 				if (p->quirks & pmac_i2c_quirk_skip)
 					break;