USB: Make file operations structs in drivers/usb const.

Making structs const prevents accidental bugs and with the proper debug
options they're protected against corruption.

Signed-off-by: Luiz Fernando N. Capitulino <lcapitulino@mandriva.com.br>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/input/hiddev.c b/drivers/usb/input/hiddev.c
index f6b839c..a2b419d 100644
--- a/drivers/usb/input/hiddev.c
+++ b/drivers/usb/input/hiddev.c
@@ -722,7 +722,7 @@
 	return -EINVAL;
 }
 
-static struct file_operations hiddev_fops = {
+static const struct file_operations hiddev_fops = {
 	.owner =	THIS_MODULE,
 	.read =		hiddev_read,
 	.write =	hiddev_write,