msm: kgsl: Perform cache operation with kernel address

Kernel should never access untrusted pointers directly.
If the address is not mapped to kernel, map to kernel
address space and perform cache related operation.

Change-Id: I433befcde620e51b8ec17954ddb710f6084e0592
Signed-off-by: Hareesh Gundu <hareeshg@codeaurora.org>
Signed-off-by: Archana Sriram <apsrir@codeaurora.org>