msm: kgsl: Do not use uint64_t in header included by user space

Do not use uint64_t in header file that can be included by user
space application as the user space application may not have
uint64_t defined.

Change-Id: I19b710958f527290a2d8b4d4e17203486e01a2f3
Signed-off-by: Shubhraprakash Das <sadas@codeaurora.org>