Use the dev_dbg dynamic infrastructure instead of rolling our own custom
debug logic.  This is needed as CONFIG_USB_DEBUG is now gone.

Cc: Mauro Carvalho Chehab <m.chehab@samsung.com>
Cc: Sean Young <sean@mess.org>
Cc: Hans Verkuil <hans.verkuil@cisco.com>
Cc: Jonathan McCrohan <jmccrohan@gmail.com>
Cc: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>