msm: kgsl: Add a flag to context struct for bad timestamp waits

If the userspace calls the waittimestamp ioctl with an invalid
timestamp for a context then set a flag indicating that the ioctl
was called with an invalid ts. If the flag is set then do not
print error message about this ioctl being called with an invalid
timestamp. This is required to prevent the kernel log from
spamming with error messages and causing a watchdog.

CRs-fixed: 374586
Change-Id: I3e599c893145fc4b603b19a517f431c1f452ce02
Signed-off-by: Shubhraprakash Das <sadas@codeaurora.org>