usb: gadget: fix for a typo that conveys logically-inverted information.

Upon calling usb_ep_autoconfig_release(), the endpoint becomes *not
valid*.

Signed-off-by: Ajay Garg <ajaygargnsit@gmail.com>
Link: https://lore.kernel.org/r/20210909120624.77557-1-ajaygargnsit@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>