msm: bam_dmux: fix duplicate dfab vote

If the A2 power collapse feature is disabled, bam_dmux will likely vote
for dfab twice in a row, which should not happen.  This is because the
first vote is done when it is assumed that A2 PC will be enabled, and that
vote is not accounted for in the internal driver state when A2 PC is
disabled.

CRs-Fixed: 361733
Change-Id: Ib3b1063dde5f3542b81d699b53d3e2cb35e40fa7
Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>