[U-Boot] OMAP5 xHCI support

This patch series adds the OMAP5 xHCI support.

It is has dependencies on the following patches

http://patchwork.ozlabs.org/patch/268797/ http://patchwork.ozlabs.org/patch/268766/

At this time the uBoot USB engine does not allow more then one stack to be enabled at a time. Since the ethernet port is on the eHCI port I have opt'd to keep the eHCI enabled over the xHCI.

To enable the xHCI stack for OMAP add the following configs in addition to the standard USB defines. NOTE: eHCI must be disabled

CONFIG_USB_XHCI CONFIG_USB_XHCI_OMAP CONFIG_PALMAS_USB_SS_PWR