[media] s2255drv: cleanup vidioc_enum_fmt_cap()

"f" wasn't checked consistently, so static checkers complain.  This
function is always called with a valid "f" pointer, so I have removed
the check.

Also the indenting was messed up.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Dean Anderson <linux-dev@sensoray.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>