msm: kgsl: Make sure kmemleak tool does not report incorrect mem leak.

Certain memory allocations are not properly tracked by kmemleak tool,
which makes it to incorrectly detect memory leak. Notify the tool by using
kmemleak_not_leak() to ignore the memory allocation so that incorrect leaks
report are avoided.

Change-Id: Id3beea7d99aedc10d9d8d74e5dad384e03abf4f2
CRs-Fixed: 334294
Signed-off-by: Anshuman Dani <adani@codeaurora.org>