tegra: usb: Add support for Tegra USB peripheral

This adds basic support for the Tegra2 USB controller. Board files should
call board_usb_init() to set things up.

Configuration is performed through the FDT, with aliases used to set the
order of the ports, like this fragment:

        aliases {
		/* This defines the order of our USB ports */
                usb0 = "/usb@0xc5008000";
                usb1 = "/usb@0xc5000000";
        };

drivers/usb/host files ONLY: Acked-by: Remy Bohmer <linux@bohmer.net>
Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>

lib/fdtdec.c

@@ -37,6 +37,7 @@ DECLARE_GLOBAL_DATA_PTR;
 #define COMPAT(id, name) name
 static const char * const compat_names[COMPAT_COUNT] = {
 	COMPAT(UNKNOWN, "<none>"),
+	COMPAT(NVIDIA_TEGRA20_USB, "nvidia,tegra20-ehci"),
 };
 
 const char *fdtdec_get_compatible(enum fdt_compat_id id)