ASoC: wcd9335: use proper codec mask value

Codec register mask used for boost register is same as
the register value. Change the mask to 0xff so that
existing values of the register will be cleared and
desired value is set.

Change-Id: I9baf2a32b00cf123057bdd28199255e09d3646e3
Signed-off-by: Viraja Kommaraju <virajak@codeaurora.org>