media: smiapp: Use __v4l2_ctrl_handler_setup()

Use unlocked __v4l2_ctrl_handler_setup() in order to make the
control setup atomic.

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