drivers: Fix compiler warnings

Fix uninitialized variable warnings with the config option
CC_OPTIMIZE_FOR_PERFORMANCE enabled.

Change-Id: I14332ea7068071e8abaf8b1fd12820f46d0e9573
Signed-off-by: Channagoud Kadabi <ckadabi@codeaurora.org>
Signed-off-by: Runmin Wang <runminw@codeaurora.org>