Various fixes from initial attempts to integrate the SAMA5 SSC/I2C driver with the I2C character driver loopback test

Add an I2S character driver.  This driver is only intended to support I2S testing and is inappropriate for use with real I2S devices

STM32 OTG FS device and host drivers extended so that they can support either the OTG FS peripheral or the OTG HS peripheral (in FS mode).  This was done as a quick way to get USB support on the STM32F429 which has only OTG HS.  From Ken Pettit

STM32 F1 USB device:  Fix handling of EP0 start for large buffers; Add support for decoded USB trace strings.  From Davice Sidrane

Extend stack debug logic to include IDLE and interrupt stacks.  Also color the heap as well.  Based on suggestions from David Sidrane

arch/arm/src/stm32/stm32_usbdev.c: On a failure to bind the class driver, the driver reference was being nullified too soon.  This caused an exception in usbdev_reset() later.  The driver reference will be null
ified later usbdev_unregister when the caller gets the error.  From David Sidrane