[media] Doc*/media/uapi: fix control name

V4L2_CID_EXPOSURE_BIAS does not exist, fix documentation.

Signed-off-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>