msm: kgsl: Fix conditional GPU interrupts to fire only for waiting context

Conditional interrupts were not getting fired at the correct time when
using per context timestamps.  When a context was waiting on a timestamp,
the interrupt was being fired on the global timestamp rather than the per
context timestamp.  Now the interrupt is fired on the per context
timestamp.

CRs-Fixed: 340620
Change-Id: I8393ca74aabfe4b711b61efb023d38d6ab852eec
Signed-off-by: Carter Cooper <ccooper@codeaurora.org>