drivers: slimbus: slim-msm-ngd: Set 32 bit DMA mask

As ZONE_DMA32 is disabled, we need to set 32 bit dma
mask in slimbus driver as a means to get only 32 bit
dma addresses. Otherwise we might get a address which is
more than 32 bit, this results in failures as slimbus
uses bam for transfers and bam supports 32 bit addresses.

Change-Id: I7a9688285034f8de9c2ad4860aeeefc86d387f45
Signed-off-by: Prudhvi Yarlagadda <pyarlaga@codeaurora.org>