[PATCH] sab: consolidate kmem_bufctl_t

This is used only in slab.c and each architecture gets to define whcih
underlying type is to be used.

Seems a bit silly - move it to slab.c and use the same type for all
architectures: unsigned int.

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>