msm: camera: Memset the data structure

This change memsets the flush arguments struct before
populating the necessary fields. Also as part of icp flush
removing log that accesses pending req even when the pending
req count might be 0.

Change-Id: I16f9b1c1bfa6f863a32d305e163b10883e78b212
Signed-off-by: Karthik Anantha Ram <kartanan@codeaurora.org>
Signed-off-by: Vishalsingh Hajeri <vhajeri@codeaurora.org>