V4L/DVB (12756): af9015: fix typo in register compare

And mask should be 0xff00 instead of 0xae00.

Thanks to Jochen Friedrich <jochen@scram.de> for pointing this.

Cc: Jochen Friedrich <jochen@scram.de>
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>