Tegra20 USB has 3 PHY instances. Instance 0 is based on
legacy PHY interface and other two are standard interfaces.

As instance number was used to differentiate legacy from
standard interfaces, used DT param to get this info and
processed accordingly.
Signed-off-by: NVenu Byravarasu <vbyravarasu@nvidia.com>
Acked-by: NFelipe Balbi <balbi@ti.com>
Signed-off-by: NStephen Warren <swarren@nvidia.com>