[POWERPC] cell: Convert #include of asm/of_{platform, device}.h into linux/of_{platform, device}.h.

Signed-off-by: Jon Loeliger <jdl@freescale.com>
Acked-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>