fbdev: kconfig: replace PPC_OF with PPC

The PPC_OF is a ppc specific option which is used to mean that the
firmware device tree access functions are available. Since all the
ppc platforms have a device tree, it is aways set to 'y' for ppc.
So it makes no sense to keep a such option in the current kernel.
Replace it with PPC.

Signed-off-by: Kevin Hao <haokexin@gmail.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

drivers/video/fbdev/Kconfig

@@ -479,7 +479,7 @@ config FB_ATARI
 
 config FB_OF
 	bool "Open Firmware frame buffer device support"
-	depends on (FB = y) && (PPC64 || PPC_OF) && (!PPC_PSERIES || PCI)
+	depends on (FB = y) && PPC && (!PPC_PSERIES || PCI)
 	select FB_CFB_FILLRECT
 	select FB_CFB_COPYAREA
 	select FB_CFB_IMAGEBLIT