media: uvcvideo: Fix event flags in uvc_ctrl_send_events

If there is an event that needs the V4L2_EVENT_CTRL_CH_FLAGS flag, all
the following events will have that flag, regardless if they need it or
not.

This is because we keep using the same variable all the time and we do
not reset its original value.

Cc: stable@vger.kernel.org
Fixes: 805e9b4a ("[media] uvcvideo: Send control change events for slave ctrls when the master changes")
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://lore.kernel.org/r/20241114-uvc-roi-v15-1-64cfeb56b6f8@chromium.org


Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>