[media] media: remove the setting of the flag V4L2_FL_USE_FH_PRIO

Since all the drivers that use `struct v4l2_fh' use the core
priority checking, the setting of the flag in the drivers can
be removed.

Signed-off-by: Ramakrishnan Muthukrishnan <ramakrmu@cisco.com>
Reviewed-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>