serial: msm_geni_serial: Correct memory access operation

Serial driver is writing into register without considering the
base address of UART and mistakenly passes the structure directly.
This wrongly writes into register, hence correct it by passing
actual base address.

Change-Id: Ide30305915c7300f9cf4611e8ac4b4ec10c8d46b
Signed-off-by: Mukesh Kumar Savaliya <msavaliy@codeaurora.org>