drivers/usb/storage/realtek_cr.c: fix build

Remove unused local `us', which broke the build.  Also nuke an unneeded
cast.

Repairs commit 191648d0 ("usb: storage: Convert US_DEBUGP to
usb_stor_dbg").

Cc: Joe Perches <joe@perches.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/usb/storage/realtek_cr.c

@@ -933,14 +933,11 @@ static int realtek_cr_autosuspend_setup(struct us_data *us)
 
 static void realtek_cr_destructor(void *extra)
 {
-	struct rts51x_chip *chip = (struct rts51x_chip *)extra;
-	struct us_data *us;
+	struct rts51x_chip *chip = extra;
 
 	if (!chip)
 		return;
 
-	us = chip->us;
-
 #ifdef CONFIG_REALTEK_AUTOPM
 	if (ss_en) {
 		del_timer(&chip->rts51x_suspend_timer);