The MMC clock we thought we had until now are actually not one but three
different clocks.

The main one is unchanged, and will have three outputs:
  - The clock fed into the MMC
  - a sample and output clocks, to deal with when should we output/sample data
    to/from the MMC bus

The phase control we had are actually controlling the two latter clocks, but
the main MMC one is unchanged.

We can adjust the phase with a 3 bits value, from 0 to 7, 0 meaning a 180 phase
shift, and the other values being the number of periods from the MMC parent
clock to outphase the clock of.
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>