[PATCH] Kconfig fix (ppc32 SMP dependencies)

ppc SMP is supported only for 6xx/POWER3/POWER4 - i.e. ones that have
PPC_STD_MMU.  Dependency fixed.

Signed-off-by: Al Viro <viro@parcelfarce.linux.theplanet.co.uk>
Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>