msm: kgsl: Retry process private open in a special failure case

Currently, process private open/kgsl_open fails in case same pid
previous process private refcount is zero but destroy didn't
complete yet. In this failure case, as we are sure that destroy
is triggered and just pending to finish, retry process private
open again after some delay to ensure process private open is
successful.

Change-Id: I7cd8a2b7d64d9472121ffa8633d0621923f5ec89
Signed-off-by: Deepak Kumar <dkumar@codeaurora.org>