V4L/DVB (5217): Zl10353: Implement TRL nominal rate calculation

Implement trl nominal rate calculation to Zarlink ZL10353 demod,
based on calculation used in Zarlink MT352.
This adds support for 6 and 8MHz bandwidth transponders.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Chris Pascoe <c.pascoe@itee.uq.edu.au>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>