mb862xxfb: use CONFIG_OF instead of CONFIG_PPC_OF

With this change, the driver builds fine on Microblaze, which helps
allyesconfig compile tests.

I did not test sparc, but the change should have the same effect there.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Anatolij Gustschin <agust@denx.de>
Tested-by: Anatolij Gustschin <agust@denx.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Michal Simek <monstr@monstr.eu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/video/mb862xx/mb862xxfb.c

@@ -19,7 +19,7 @@
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/pci.h>
-#if defined(CONFIG_PPC_OF)
+#if defined(CONFIG_OF)
 #include <linux/of_platform.h>
 #endif
 #include "mb862xxfb.h"