serial: sccnxp: Improve error message if regulator_disable() fails

serial: sccnxp: Improve error message if regulator_disable() fails

Returning an error code from .remove() makes the driver core emit the
little helpful error message:

	remove callback returned a non-zero value. This will be ignored.

and then remove the device anyhow.

So replace the error return (and with it the little helpful error
message) by a more useful error message.

Fixes: 31815c08fc90 ("serial: sccnxp: Replace pdata.init/exit with regulator API")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20231110152927.70601-3-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>