msm_serial_hs: remove unused code

Remove support for all pre BLSP Hardware such as Data Mover
DMA and GSBI. Clean up all checks for non BLSP hardware and
refactor the code.

CRs-Fixed: 647392
Change-Id: I2df3d036b0ce4a16d5a693059ca4bc51f17eef85
Signed-off-by: Naveen Kaje <nkaje@codeaurora.org>