serial: qcom-geni: Add support for 8 Mbps baud rate

Current GENI UART driver supports Max Baud rate up to 4 Mbps.
Add support to increase maximum baud rate to 8 Mbps.

Signed-off-by: Jyothi Kumar Seerapu <quic_jseerapu@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20250523103721.5042-1-quic_jseerapu@quicinc.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>