[PATCH] uml: fixups for "reuse i386 cpu-specific tuning"

A few fixups - show the new submenu only for x86 subarchitecture (it does not
make sense to show it for x86_64 users) and remove X86_CMPXCHG, which is now a
duplicate of Kconfig.i386, even though Kconfig doesn't complain (we also miss
the dependency on !M386 CPU).

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Acked-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>