drivers/scsi/pm8001/pm8001_ctl.c: avoid world-writable sysfs files.
In line with practice for module parameters, we're adding a build-time
check that sysfs files aren't world-writable.
Cc: Lindar Liu <firstname.lastname@example.org>
Cc: James Bottomley <JBottomley@Parallels.com>
Signed-off-by: Rusty Russell <email@example.com>