This adds a new mode WM8904_CLK_AUTO which automatically enables the FLL
if a frequency different than the MCLK is set.

These additions make the codec work with the simple-card driver in
general and especially in systems where the MCLK doesn't match the
required clock.
Signed-off-by: Michael Walle <michael@walle.cc>
Acked-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20191108203152.19098-1-michael@walle.ccSigned-off-by: Mark Brown <broonie@kernel.org>