ARM: tegra: add clocks properties to USB PHY nodes

The patch to add USB PHY nodes to device tree was written before Tegra
supported the clocks property in device tree. Now that it does, add the
required clocks properties to these nodes.

This will allow all clk_get_sys() calls in tegra_usb_phy.c to be replaced
by clk_get(phy->dev, clock_name), as part of converting the PHY driver to
a platform driver.

Acked-by: Venu Byravarasu <vbyravarasu@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>