serial: 8250_omap: Set the console genpd always on if no console suspend

serial: 8250_omap: Set the console genpd always on if no console suspend

If the console suspend is disabled, the genpd of the console shall not
be powered-off during suspend.
Set the flag GENPD_FLAG_ALWAYS_ON to the corresponding genpd during
suspend, and restore the original value during the resume.

Signed-off-by: Thomas Richard <thomas.richard@bootlin.com>
Link: https://lore.kernel.org/r/20231017130540.1149721-1-thomas.richard@bootlin.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>