USB: fix minor nit in usbfs checking

One minor nit did show up, though. The patch below
seems to make more sense than the code does without it.

Signed-off-by: Mark Lord <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/core/devio.c

···
 	if (__get_user(uptr, &uurb->buffer))
 		return -EFAULT;
 	kurb->buffer = compat_ptr(uptr);
-	if (__get_user(uptr, &uurb->buffer))
+	if (__get_user(uptr, &uurb->usercontext))
 		return -EFAULT;
 	kurb->usercontext = compat_ptr(uptr);