[media] smiapp: Set 64-bit integer control using v4l2_ctrl_s_ctrl_int64()

Don't manipulate struct v4l2_ctrl directly. Instead, use
v4l2_ctrl_s_ctrl_int64() to change the values.

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