msm: camera: Add defensive check in ISPIF driver

In case of error handling, call ispif release only if ispif handle
is valid. In case of mm-qcamara-daemon crash when camera is not open,
these handles are not valid. Hence it leads to kernel crash in ispif
release handler.

Change-Id: Ifb402b6907052594d12fcf9495694e6c5184af1b
Signed-off-by: Sreesudhan Ramakrish Ramkumar <srramku@codeaurora.org>