msm: bam: Use memset_io instead of memset

Currently memset is used to zero out the descriptor and data FIFOs,
however if the memory is IO-mapped, memset may cause alignment
faults.
Use memset_io to accommodate the possibility of IO-mapped memory.

Change-Id: I8d513c1c7f4bdd3df6f4072f989536d10dfe8976
Signed-off-by: Azhar Shaikh <azhars@codeaurora.org>