tty: serial: msm_geni_serial: Add SSR support for SSC QUPs

This change is related to SSC QUP SSR.
Common driver will get initial notification about SSR and
respective bus client driver will get called accordingly for
SSR down and up sequence. For UART this feature gets controlled
with dtsi flag entry per uart node.

Change-Id: I31407dbce4030af8ca71e6f8cc1f113fac821680
Signed-off-by: venkata manasa kakarla <venkka@codeaurora.org>