msm: kgsl: Poll a6x crashdumper register memory for status

Use a6x crashdumper register memory end location to know
the crashdumper status completion. This will avoid AHB
traffic while crashdumper was active in snapshot dumping
and fixes the slave timeout issue.

Change-Id: Ic24e75557297c6a1a3f2ad7893f4d8d308f9943c
Signed-off-by: Hareesh Gundu <hareeshg@codeaurora.org>