serial: qcom-geni: Enable PM runtime for serial driver

serial: qcom-geni: Enable PM runtime for serial driver

The GENI serial driver currently handles power resource management
through calls to the statically defined geni_serial_resources_on() and
geni_serial_resources_off() functions. This approach reduces modularity
and limits support for platforms with diverse power management
mechanisms, including resource managed by firmware.

Improve modularity and enable better integration with platform-specific
power management, introduce support for runtime PM. Use
pm_runtime_resume_and_get() and pm_runtime_put_sync() within the
qcom_geni_serial_pm() callback to control resource power state
transitions based on UART power state changes.

Signed-off-by: Praveen Talari <praveen.talari@oss.qualcomm.com>
Link: https://patch.msgid.link/20251110101043.2108414-4-praveen.talari@oss.qualcomm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>