defconfig: msm: Enable BAM DMUX driver for msm8937

Enable Bam dmux driver to support the multiple clients to send/receive
data faster to modem by using single A2-BAM physical connection.

CRs-Fixed: 2144615
Change-Id: I4c6f1df6da3f824fb4712a5a7dcebcd48e260435
Signed-off-by: Arun Kumar Neelakantam <aneela@codeaurora.org>