msm: sps: enable BAM DMA client to control BAM DMA clock

For power saving reason, SPS driver will turn off the clock of
BAM DMA after the initial configuration. A new API is provided
to BAM DMA clients to vote for or relinquish BAM DMA clock when
they start/stop using BAM DMA.

Change-Id: I03f8a6cfa19c1722ca4e92e0785ca309fdd10ba2
Signed-off-by: Yan He <yanhe@codeaurora.org>