hm2: add support for muxed encoder version 4

Signed-off-by: Michael Geszkiewicz <micges@wp.pl>
hm2: muxed encoder: add support for FilterRate and Muxed Skew register.

FilterRate: sets the sampling rate for all quadrature counters input filters.
MuxedSkew: Version 4 and greater muxed encoders have 4 bit muxed data deskew register
This delays the sampling time of muxed encoder data by 0 to 15 ClockLow
periods to accomodate long cables and isolation delays and allow higher
multiplex rates.

Signed-off-by: Michael Geszkiewicz <micges@wp.pl>
hm2: add support for 5i24 board

Signed-off-by: Michael Geszkiewicz <micges@wp.pl>