[media] smiapp: Implement support for autosuspend

Delay suspending the device by 1000 ms by default. This is done on
explicit power off through s_power() callback, through releasing the
file descriptor, NVM read or when the probe finishes.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>