viafb: PLL value cleanup

This is a big change of how PLL values are handled on the road to
dynamic PLL value generation. The table was converted automatically in
the relevant parameters for frequency generation. Sadly there were some
bits set whose meaning is unknown. Those differences are documented
but ignored as the unichrome code implies that they are not important
(a big thanks to Luc for his amazing work).
The PLL values for 31490000 and 133308000 are deleted as they were more
than 5% off and not used anyway. The values for CX700@60466000 and
VX855@153920000 are corrected as they were wrong and easily correctable
as enough correct values was available because CX700 and VX855 support
the same values only with a little difference in hardware format.
All remaining values are not more than 2% off.
Additionally the surrounding code is changed as needed especially the
byte order of the values written to hardware to allow nicer conversion
functions.
This is mostly a change preparing for dynamic PLL generation and the two
corrected values aside no runtime change is expected.
Signed-off-by: NFlorian Tobias Schandinat <FlorianSchandinat@gmx.de>
Cc: Joseph Chan <JosephChan@via.com.tw>