usb: host: Add EHCI driver for NVIDIA Tegra SoCs

The Tegra 2 SoC has 3 EHCI compatible USB controllers. This patch adds
the necessary glue to allow the ehci-hcd driver to work on Tegra 2
SoCs.

The platform data is used to configure board-specific phy settings and
to configure the operating mode, as one of the ports may be used as a otg
port. For additional power saving, the driver supports powering down the
phy on bus suspend when it is used, for example, to connect an internal
device that use an out-of-band remote wakeup mechanism (e.g. a gpio).

Signed-off-by: Benoit Goby <benoit@android.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>