[media] smiapp: Clean up smiapp_set_format()

smiapp_set_format() has accumulated a fair amount of changes without a
needed refactoring, do the cleanup now. There's also an unlocked version of
v4l2_ctrl_range_changed(), using that fixes a small serialisation issue with
the user space interface.

__v4l2_ctrl_modify_range() is used instead of v4l2_ctrl_modify_range() in
smiapp_set_format_source() since the mutex is now held during the function
call.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>