msm: kgsl: a2xx: Check the right interrupt status bits

Check the actual interrupt status bits in a2xx_irq_pending instead
of reading the mask registers which were always set and returning
true. Troutslap for the original author (me).

CRs-fixed: 467381

Conflicts:

	drivers/gpu/msm/adreno_a2xx.c

Change-Id: Ic0dedbada1c5fa64548221718c1eaf9b6eaaa1e8
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Hareesh Gundu <hareeshg@codeaurora.org>

Conflicts:
	drivers/gpu/msm/adreno_a2xx.c