msm: camera: isp: Move req out of pending list before start

This change moves init request out of pending list before
starting hardware. Currently if we receive the first SOF and
RUP IRQs before start_dev routine has completed, we miss
pushing out the init request to free list on the first RUP as
wait list will be empty.

Change-Id: Icd53e0ebe0d12e264172058d836e6ccfcb7df0c2
Signed-off-by: Venkat Chinta <vchinta@codeaurora.org>