Ensure all mask bits are clear before setting new value.
Signed-off-by: NAxel Lin <axel.lin@gmail.com>
Acked-by: NDong Aisheng <b29396@freescale.com>
Acked-by: NLiam Girdwood <lrg@ti.com>
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>