UPSTREAM: mm/slab: use more appropriate condition check for debug_pagealloc

UPSTREAM: mm/slab: use more appropriate condition check for debug_pagealloc

debug_pagealloc debugging is related to SLAB_POISON flag rather than
FORCED_DEBUG option, although FORCED_DEBUG option will enable
SLAB_POISON.  Fix it.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Bug: 64145065
(cherry-picked from 40323278b557a5909bbecfa181c91a3af7afbbe3)
Change-Id: I4a7dbd40b6a2eb777439f271fa600b201e6db1d3
Signed-off-by: Paul Lawrence <paullawrence@google.com>