usb: fix typo in drivers/usb

Correct spelling typo in debug messages within drivers/usb.

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>