V4L/DVB (9937): cx18: Use a consistent crystal value for computing all PLL parameters

Use a consistent crystal value of 28.636360 MHz for computing all PLL
parameters so clocks don't have relative error due to assumed crystal
value mismatches.  Also aimed to have all PLLs run their VOCs at close to
400 MHz to minimze the error of these PLLs as frequency synthesizers. Also
set the VDCLK and AIMCLK PLLs to sane values before the APU and CPU firmware
are loaded.  Also fixed I2S Master clock dividers.

Many thanks to Mike Bradley and Jeff Campbell for reporting this problem and
suggesting the solution, researching and experimenting, and performing
extensive testing to support their suggested solution.

Reported-by: Jeff Campbell <jac1dlists@gmail.com>
Reported-by: Mike Bradley <mike.bradley@incanetworks.com>
Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>