msm: kgsl: Use readl_poll_timeout() for crashdumper status

Crashdumper required sometime to finish all register dumps.
Hence add minimum 100msec sleep time before we start polling
on crashdumper completion. Use readl_poll_timeout() for
crashdumper completion check to reduce AHB traffic.

Change-Id: I112466e67760f26e73e7c8a69bf466ce8b8ef09b
Signed-off-by: Hareesh Gundu <hareeshg@codeaurora.org>