msm: msm_bus: Add new bus master id for pimem

Add new bus master id to identify the pimem bus master
for bandwidth aggregation and QoS programming done
by the bus driver.

Change-Id: I0991065984b35511c33ab4c9bd274ad465d19601
Signed-off-by: Odelu Kukatla <okukatla@codeaurora.org>