[media] s2255drv: fix some endian bugs

I don't have this hardware and I don't know the subsystem very well.  So
please review this patch carefully.  The original code definitely looks
buggy though.

Sparse complains about some endian bugs where little endian bugs are
treated as cpu endian.

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>