serial: msm_geni_serial: Add missing changes from 4.19 kernel

This change adds all missing changes on previous snapshot of
the base kernel 4.19.

Change-Id: Iaa5f338b97eb4a6194125a34119f4a089d92baa9
Signed-off-by: Mukesh Kumar Savaliya <msavaliy@codeaurora.org>