ARM: tegra: enable ULPI phy on Colibri T20

This was missed when splitting out the phy from the controller node in
commit 9dffe3be (ARM: tegra: modify ULPI reset GPIO properties).

Signed-off-by: Lucas Stach <dev@lynxeye.de>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Olof Johansson <olof@lixom.net>