[POWERPC] Rename device_is_compatible to of_device_is_compatible

This is more consistent and gets us closer to the Sparc code.

We add a device_is_compatible define for compatibility during the
change over.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/include/asm-powerpc/prom.h b/include/asm-powerpc/prom.h
index 448c5ce..fcacc88 100644
--- a/include/asm-powerpc/prom.h
+++ b/include/asm-powerpc/prom.h
@@ -162,8 +162,9 @@
 extern void finish_device_tree(void);
 extern void unflatten_device_tree(void);
 extern void early_init_devtree(void *);
-extern int device_is_compatible(const struct device_node *device,
+extern int of_device_is_compatible(const struct device_node *device,
 				const char *);
+#define device_is_compatible(d, c)	of_device_is_compatible((d), (c))
 extern int machine_is_compatible(const char *compat);
 extern const void *of_get_property(const struct device_node *node,
 				const char *name,