Merged in david_s5/nuttx/master_kinetis_usbhang (pull request #688)

kinetis:USB0 fix interrupt storm on error

The ERROR bit of USBx_ISTAT needed to be cleared once an
   error occured.

Approved-by: GregoryN <gnutt@nuttx.org>

arch/arm/src/kinetis/kinetis_usbdev.c

@@ -2793,6 +2793,7 @@ static int khci_interrupt(int irq, void *context, FAR void *arg)
       /* Clear all pending USB error interrupts */
 
       khci_putreg(USB_EINT_ALL, KINETIS_USB0_ERRSTAT);
+      khci_putreg(USB_INT_ERROR, KINETIS_USB0_ISTAT);
     }
 
   /* Service resume interrupts */