serial: qcom-geni: drop bogus runtime pm state update

The runtime PM state should not be changed by drivers that do not
implement runtime PM even if it happens to work around a bug in PM core.

With the wake irq arming now fixed, drop the bogus runtime PM state
update which left the device in active state (and could potentially
prevent a parent device from suspending).

Fixes: f3974413 ("tty: serial: qcom_geni_serial: Wakeup IRQ cleanup")
Cc: 5.6+ <stable@vger.kernel.org> # 5.6+
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Reviewed-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>