msm: camera: isp: Move initialization of completion structure in probe

Move the initialization of completion structure in probe and use
an atomic variable to track if reset was requested and only send
completion signal if it was requested, otherwise ignore the
unexpected interrupt.

CRs-Fixed: 880144
Change-Id: If8a35e4db609d7984007be69a3f27609339e4ebb
Signed-off-by: Shubhraprakash Das <sadas@codeaurora.org>