msm: kgsl: Don't call kmemleak on vmalloc memory

kmemleak doesn't work for vmalloc() memory and if the size of the
allocated scatter gather list is too big the memory will come
from vmalloc by way of kgsl_malloc() and cause a warning in
kmemleak_not_leak(). Do a vmalloc check on the pointer before
calling kemmleak_not_leak().

CRs-Fixed: 680830
Change-Id: Ic0dedbad719f8bb675fb9a0456d659be2cc43577
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>