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 <[e-mail]>
Acked-by: Bruno Prémont <[e-mail]>
Acked-by: Jiri Kosina <[e-mail]>

drivers/hid/hid-picolcd_fb.c

···
 	return count;
 }
 
-static DEVICE_ATTR(fb_update_rate, 0666, picolcd_fb_update_rate_show,
+static DEVICE_ATTR(fb_update_rate, 0664, picolcd_fb_update_rate_show,
 		picolcd_fb_update_rate_store);
 
 /* initialize Framebuffer device */