drivers: soc: qcom: Add bam dmux driver support

Added snapshot of mdm9607 bam dmux driver as of msm-3.18.c8
commit 69da6b6721b.

Change-Id: Ic90c01188cfc0e027b215a3818119998be733a36
Signed-off-by: Prasadarao Durvasula <pdurvasu@codeaurora.org>
Signed-off-by: Sivasri Kumar Vanka <sivasri@codeaurora.org>