USB: remove err() macro

I thought this had been removed years ago.  All in-kernel users of this
call have now been cleaned up and converted over to use dev_err()
instead, which is the correct thing to do.  Now that there are no users,
the macro can be removed so no one else accidentally starts to use it.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/linux/usb.h

@@ -1653,9 +1653,6 @@ do {									\
 } while (0)
 #endif
 
-#define err(format, arg...)					\
-	printk(KERN_ERR KBUILD_MODNAME ": " format "\n", ##arg)
-
 /* debugfs stuff */
 extern struct dentry *usb_debug_root;