ASoc: wcd934x: correct MAD micbias setting

As per register definition in software interface, the
bitmask for Micbias selection in wcd934x MAD setup should
be 0x07, not 0x03. Correct the bitmask setting.

Change-Id: I475d1219ae62378a90c69642f2320149d0f13885
Signed-off-by: Meng Wang <mwang@codeaurora.org>