drivers/hid/hid-picolcd_fb: 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.
Signed-off-by: Rusty Russell <email@example.com>
Acked-by: Bruno Prémont <firstname.lastname@example.org>
Acked-by: Jiri Kosina <email@example.com>