msm: camera: fd: add flush functionality

Delete the frame requests that are required to flush from pending list
and processing list. And reset hw if it is processing the request that
is required to flush.

Change-Id: Ifdbb817acbef95af3bfe29f2b98f9aed7e7a0f17
Signed-off-by: Junzhe Zou <jnzhezou@codeaurora.org>