serial: msm_geni_serial: Set clock freq correctly for RUMI

This patch adds RUMI specific changes to enable UART clock to
run at half the rate. On RUMI we do see some garbage logs when
setting the clock based on baud rate, this change is to fix
garbage RUMI console logs.


Change-Id: I47e7397f5597067a3981f75354c1f0f85f3cfe9d
Signed-off-by: Mukesh Kumar Savaliya <msavaliy@codeaurora.org>