[media] s2255: fixes in the way standards are handled

Instead of comparing against STD_NTSC and STD_PAL compare against 60 and
50 Hz formats. That's what you really want.
When the standard is changed, make sure the width and height of the format
are also updated to reflect the current standard.
Also replace the deprecated current_norm by the g_std ioctl.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>