Declare the interrupt as "one shot" so that it is masked until the end
of the threaded handler. This prevents the irq core from spitting out an
error :
  "Threaded irq requested with handler=NULL and !ONESHOT for irq 63"

This was introduced by commit "usb: phy: generic: add vbus support".
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Felipe Balbi <balbi@ti.com>