Olimex LPC1766STK: The USB host waiter stack should be configurable because it needs to be a lot depending when using a hub

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

STM32F4-Discovery: Part of logic to initialize the ELF loaded in the board startup logic.  From Leo aloe3132

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

STM32F429i-Disco: Add some missing USB host configureation.  Fix some some duplicate class registration that causes infinite loops in USB registry searches

STM32F4-Discovery: Add configuration option to select the size of the stack used with the usbhost waiter.  Needs to be bigger when a hub is supported

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.

USB HUB: Update all USB host connection waiter application threads to use the the new connection interface

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

Fix an error introduced into stm32_pwr_enablebkp().  That function must preserve the previous state of backup domain access on return.