ASoC: omap-mcbsp: Prepare for init time DAI format setting

Before commit 75d9ac46 ("ASoC: Allow DAI formats to be specified in the
dai_link") expectation for omap-mcbsp was that snd_soc_dai_set_fmt is to be
called first in machine hw_params callback before other CPU DAI functions.
Thus it was enough that only omap_mcbsp_dai_set_dai_fmt cleared the
mcbsp->regs structure.  [Note that this was pure convention, it's always
been OK to set things on init -- broonie]

Now this doesn't hold anymore since machine drivers can set the DAI format
only once on init time and thus mcbsp->regs may get out of sync when other
CPU DAI functions are modifying them dynamically with different values
between the calls. Therefore clear the accessed mcbsp->regs bits and
bitfields in other functions too.

Signed-off-by: Jarkko Nikula <jarkko.nikula@bitmer.com>
Cc: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>