[U-Boot] OMAP5 xHCI support

[Dan Murphy]

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