[PATCH] uml: fix "reuse i386 cpu optimizations"

Remove RWSEM_GENERIC_SPINLOCK, it's now defined (only if needed) by the
underlying arch/i386/Kconfig.cpu.  Leave it only for x86_64.  Even there, it's
totally wrong, as they even have the code to support XCHG_ADD.

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