V4L/DVB (6656): zl10353: store frequencies in 0.1kHz to eliminate rounding errors

Whilst reanalysing my formulas I realised it was no longer possible to get the
right values for a 36.1667MHz IF due to rounding problems.

Storing frequencies in units of 0.1kHz makes it possible to calculate these
again correctly.

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