serial: msm_geni_serial: Changes to fix console on GENI UART

Make all the register_reads/writes non-logging else considering the volume
of register accesses the console becomes slow and unstable.
The default fifo depth was incorrectly assumed causing message overwrites.
Also increase the poll iterations to avoid prematurely cancelling the
command sequencers.

Change-Id: Icc137e194d0334a710655f10a9d3115d55db80f8
Signed-off-by: Girish Mahadevan <girishm@codeaurora.org>