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.

STM32F429i Disco: (1) Fix a bad return value if the LCD driver is already initialized. (2) The LCD driver initialization is now performed during the early boot sequence.  (3) Increased the size of the message queue from 32 to 64 in the lcd configuration.  From Marco, ocram.lhark@yahoo.com.

Add support for the new DMA2D features to the STM32F429i-Disco LTDC configuration.  From Marco Krahl.