serial: ami: Mark driver struct with __refdata to prevent section mismatch

As described in the added code comment, a reference to .exit.text is ok
for drivers registered via module_platform_driver_probe(). Make this
explicit to prevent the following section mismatch warning

	WARNING: modpost: drivers/tty/amiserial: section mismatch in reference: amiga_serial_driver+0x8 (section: .data) -> amiga_serial_remove (section: .exit.text)

that triggers on an allmodconfig W=1 build.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/043afcbc94ad90079301f3c7738136a7993a1748.1711748999.git.u.kleine-koenig@pengutronix.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/amiserial.c

@@ -1578,7 +1578,13 @@ static void __exit amiga_serial_remove(struct platform_device *pdev)
 	free_irq(IRQ_AMIGA_RBF, state);
 }
 
-static struct platform_driver amiga_serial_driver = {
+/*
+ * amiga_serial_remove() lives in .exit.text. For drivers registered via
+ * module_platform_driver_probe() this is ok because they cannot get unbound at
+ * runtime. So mark the driver struct with __refdata to prevent modpost
+ * triggering a section mismatch warning.
+ */
+static struct platform_driver amiga_serial_driver __refdata = {
 	.remove_new = __exit_p(amiga_serial_remove),
 	.driver   = {
 		.name	= "amiga-serial",