Introduce a wrapper call snd_soc_update_bits_locked()
that will take the codec mutex. This call is used
when the codec mutex is not already taken.

Drivers calling snd_soc_update_bits() may wish to
make sure the codec mutex is taken from the driver.
Signed-off-by: NEero Nurkkala <ext-eero.nurkkala@nokia.com>
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>