msm: kgsl: Add chipid check of a620v1 for rbbm batch registers

This patch enables reading rbbm batch registers multiple time
when the read value is 0xdeafbead for a620_v1.
For rbbm batch registers when the reg read value is 0xdeafbead,
there is a possibility that this value could be incorrect.
To get the actual register value, retry reading the register for
several times.

Change-Id: Id12b9d2643740e4aa2b7e46c2231958128c97f6d
Signed-off-by: Pankaj Gupta <gpankaj@codeaurora.org>