ASoC: rt5677: make volume TLV closer to reality

The volume blocks have an step of 0.375dB, but TLV uses 0.01dB for
units.  Only use the resolution supported, ignoring the LSB of the
volume register.  This results in half the steps and 0.75dB per step,
but reports accurate levels through TLV.  Update the masks to reflect
that these are registers have the LSB ignored.

Signed-off-by: Dylan Reid <dgreid@chromium.org>
Signed-off-by: Mark Brown <broonie@kernel.org>