[POWERPC] ps3: Missed renames of CONFIG_PS3 to CONFIG_PPC_PS3

When renaming CONFIG_PS3 to CONFIG_PPC_PS3, a few occurrences have been
missed.

I also fixed up the alignment in arch/powerpc/platforms/Makefile.

Signed-off-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>