msm: kgsl: implement sync compare callback

The compare callback is required to test the order that
sync pts will signal. Failing to implement the compare
callback results in kernel panics for some use cases.

Change-Id: Ibea1497c12fd8cc66087ff52d3709a07793f215f
Signed-off-by: Jeff Boody <jboody@codeaurora.org>
Signed-off-by: Siddhartha Agrawal <agrawals@codeaurora.org>
(cherry picked from commit b44e3b4fb92810703ad296a5c9f829c5f86ffe4a)
Signed-off-by: Shruthi Krishna <skrish@codeaurora.org>