[media] s5p-mfc: fix a race in interrupt flags handling

Interrupt result flags have to be cleared before a hardware job is run.
Otherwise, if they are cleared asynchronously, we may end up clearing them
after the interrupt for which we wanted to wait has already arrived, thus
overwriting the job results that we intended to wait for.

To prevent this, clear the flags only under hw_lock and before running
a hardware job.

Signed-off-by: Pawel Osciak <posciak@chromium.org>
Signed-off-by: Kiran AVND <avnd.kiran@samsung.com>
Signed-off-by: Arun Kumar K <arun.kk@samsung.com>
Signed-off-by: Kamil Debski <k.debski@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>