scsi: mac_scsi: 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/scsi/mac_scsi: section mismatch in reference: mac_scsi_driver+0x8 (section: .data) -> mac_scsi_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/e41d10906948a980e985f6065485445d9bbbd2f7.1711746359.git.u.kleine-koenig@pengutronix.de


Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>