SLUB: clean up krealloc

We really do not need all this gaga there.

ksize gives us all the information we need to figure out if the object can
cope with the new size.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>