V4L/DVB (7952): AU6610: various cosmetic changes

- update license comments
- change MODULE_DESCRIPTION from device specific to chipset specific
- correct debug switch from deb_rc to deb_info
- correct MPEG2 stream interval from 1.25 to 1
- change frontend_attach error code from -EIO to -ENODEV

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>