SAMA5 OHCI:  Fix semaphore handling bug.  OHCI is now function by itself again after changes to integrate with EHCI

SAMA5: EHCI now handles low- and full-speed connections by giving them to OHCI; OHCI now uses the work queue to defer interrupt processing; If both OHCI and EHCI are enabled, EHCI is the master of the UHPHS interrupt

SAMA5:  Major restructuring of the the OHCI driver drivers to better handle the multiple root hub ports and concureent transfers on each port.

Separate wait() and enumerate() methods from struct usbhost_driver_s and move to new interface, struct usbhost_connection_s.  This is part of the necessary restructuring of the USB host interface to support multiple root hub ports.

Add untested OHCI driver for the SAMA5; structure naming and header files for USB host initialization prototypes

Serial FIONREAD, FIONWRITE, and TERMIOS I/O processing from Mike Smith, Andrew Tridgell, and and Lorenz Meier

MMC/SD SDIO:  Correct return values when multiple block transfers are suppressed.  From Andrew Tridgell via Lorenz Meier

SAMA5: Add PIO interrupt support.  Massive name changes for consistency in PIO vs GPIO naming.  SAMA5D3x-EK:  Add support for SD card detection PIO interrupts

SAMA5:  SPI Driver + AT25 FLASH work; SAM3/4:  Correct an error, SPI will not be correctly configured if CONFIG_SPI_OWNBUS=n