soc: msm_audio_ion: add mask for Stream ID

SMMU SID may contain multiple identifiers for hardware to properly
identify the Context Bank in the SMMU. However, only the Stream ID
part of the overall SMMU SID needs to be appended to IOVA address
of shared audio buffers, and sent to ADSP.
Add a mask for identify the Stream ID part in SMMU SID.

Change-Id: I99b8c5e379730bc06f8f90eff3958f0f5438f6e8
Signed-off-by: Banajit Goswami <bgoswami@codeaurora.org>