msm: Camera: clear control queue

Clear control queue everytime before entering wait in msm_control as
there might be invalid payloads in the queue and this can lead to
not waiting at all and exit before the valid command completes.

Change-Id: I34991968cb6bb9c2978bcea4d8ce641894cc2453
Signed-off-by: Manogna Reddy Alle <cmalle@codeaurora.org>