msm: vidc : report PC_PREP failure as SYS_ERROR

When prepare for power collapse command fails, firmware is in
unusable state. This will make the driver unusable. This commit
reports this failure as SYS_ERROR resulting in unloading the
driver and firmware so next session can be opened successfully.

Change-Id: I849c2f8e98621bdff6ca4dddfd859a916e16dcb3
Signed-off-by: Ashray Kulkarni <ashrayk@codeaurora.org>