Register "micbias1" and "micbias2" to supply widgets as modern drivers do.

This should not cause any (new) issues for existing users of the codec,
since micbias support is broken anyways. Micbias support needs the
RT5645_MICBIAS?_POW_CTRL_SEL bits in the RT5645_GEN_CTRL2 register to be
updated when enabled/disabled which we currently do not do.

The updating of these bits will be fixed in a follow-up commit.
Signed-off-by: NBard Liao <bardliao@realtek.com>
Signed-off-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NMark Brown <broonie@kernel.org>