Move the control mapping to uvc_ctrl.c. This way we do not have
references to UVC controls or V4L2 controls in uvc_driver.c.

This also fixes a bug introduced in commit 38207560 ("media:
uvcvideo: Limit power line control for Quanta UVC Webcam"). The
offending commit caused the power line control menu entries to have
incorrect indices compared to the V4L2_CID_POWER_LINE_FREQUENCY_*
enumeration. Now that the limited mapping reuses the correct menu_info
array, the indices correctly map to the V4L2 control specification.

Fixes: 38207560 ("media: uvcvideo: Limit power line control for Quanta UVC Webcam")
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>