Some USB ports can support host and device operation. We add the dr_mode
property (as found in Freescale) for this.

One USB port has a 'legacy mode', left over from the days of pre-Tegra
chips. I don't believe this is actually used, except that we must know
to turn this off in the driver.
Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Olof Johansson <olof@lixom.net>