hal: Fix sidetone sequence during voice call

When sidetone is enabled during voice call, the RX and TX path mixer
controls are issued back to back, this causes the codec path to be
enabled from TX to RX as the internal loopback for sidetone exists. Due
to enabling this path, pop noise is observed on headphones. This issue
is fixed by treating sidetone as special case and changing the enable
and disable sequence of sidetone mixer controls.

CRs-fixed: 839663
Change-Id: I7aea55af963cf939286e5b349ff25fd783314679
Signed-off-by: Bhalchandra Gajare <gajare@codeaurora.org>