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/mon/usb_mon.h b/drivers/usb/mon/usb_mon.h
index 33678c2..50efc8e 100644
--- a/drivers/usb/mon/usb_mon.h
+++ b/drivers/usb/mon/usb_mon.h
@@ -53,7 +53,7 @@
 
 extern struct mutex mon_lock;
 
-extern struct file_operations mon_fops_text;
-extern struct file_operations mon_fops_stat;
+extern const struct file_operations mon_fops_text;
+extern const struct file_operations mon_fops_stat;
 
 #endif /* __USB_MON_H */