msm: kgsl: Correct the refcount on current process PID

BugLink: https://bugs.launchpad.net/bugs/1931727



In kgsl_process_private_new() function there is inconsistency
in the refcount of current process PID. Fix this to avoid
overflowing of reference counter leading to use after free
of this struct.

Change-Id: I6291b9a05e139337e7f8471d0f9409fc839969a3
Signed-off-by: Archana Sriram <apsrir@codeaurora.org>
(cherry picked from commit bbf5735f34901952a87b2cbe557564325d755c38)
Signed-off-by: Shrirang Bagul <shrirang.bagul@canonical.com>