msm: bam_dmux: Support multiplatform

Convert to support multiplatform kernels. This requires drivers to be
located in generic functionality directories instead of specific mach
directories.

Move the bam_dmux driver to the drivers/soc/qcom location to
support multiplatform.

Change-Id: I0188ccf8adaf2d00c7298666991e38eafcc6c710
Signed-off-by: Arun Kumar Neelakantam <aneela@codeaurora.org>