slub: Simplify control flow in __slab_alloc()

Simplify control flow a bit avoiding nesting.

Change-Id: I68ca675217885e320cd4193c81f87c70bcb47aad
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Merge "slub: Simplify control flow in __slab_alloc()" into android-4.4