serial: msm_serial_hs: set the DMA mask and the coherent DMA mask

Basically, the fact that the coherent DMA mask value
wasn't set caused the driver to fall back to SWIOTLB.
For correct operation, lets call the
dma_set_mask_and_coherent() to properly set
the mask for both streaming and coherent, in
order to inform the kernel about the devices
DMA addressing capabilities.

Change-Id: I522fde8f78c01be55e91715769b4f16a28bca724
Signed-off-by: Chetan C R <cchinnad@codeaurora.org>