USB host: If the implementation of the disconnect method frees the EP0 endpoint, then it must nullify it in the port structure

USB host:  Need to include the port structure when disconnecting, otherwise may destroy a root hub port

SAM PIO: sam_pio.h needs to include chip/sam_memorymap.h in order to resolve some conditional logic properly

Added missing EXTI definitions for the STM32 F3; Correct an error the port D base address in the STM32 F3 and F37 memory maps.  From Greg Meiste.

EFM32 USB host: Add missing trace data and some missing connection-related logic; update a configuration

USB HUB: Fix a deadlock that can occur if the HCD and the HUB try to share the high priority work queue.  Now how work must be done on the low priority work queue.

STM32 PVD: Adds support for STM32's Programmable Voltage Detector feature. I put register access behind CONFIG_STM32_ENERGYLITE as have not checked F1/F2/F4 etc. manuals. Tested on STM32L1. PVD interrupt looks generic, at least #defines it needs are in headers for every chip variant.  By Dmitry Nikolaev, submitted by Juha Niskanen.

ECHI HCDs: Separate logic used in synchronous transfers so that it can be used in forthcoming asynchronous transfer

Port hub support to LPC31 from SAMA5; Updated Olimex-LPC-H3131 for hub support and refresh configurations

Copy some control port framework from LPC17 to SAMA5 OHCI; Copy some speed handling from SAMA5 OHCI to LPC17