usb: Spelling s/disconnet/disconnect/

Fix misspellings of "disconnect".

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Peter Chen <peter.chen@nxp.com>
Link: https://lore.kernel.org/r/20191024152747.30617-1-geert+renesas@glider.be


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