dt-bindings: phy: tegra: Add Tegra186 support

Extend the bindings to cover the set of features found in Tegra186. Note
that, technically, there are four more supplies connected to the XUSB
pad controller (DVDD_PEX, DVDD_PEX_PLL, HVDD_PEX and HVDD_PEX_PLL), but
the power sequencing requirements of Tegra186 require these to be under
the control of the PMIC.

Reviewed-by: JC Kuo <jckuo@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

Documentation/devicetree/bindings/phy/nvidia,tegra124-xusb-padctl.txt

@@ -36,11 +36,20 @@ Required properties:
   - Tegra124: "nvidia,tegra124-xusb-padctl"
   - Tegra132: "nvidia,tegra132-xusb-padctl", "nvidia,tegra124-xusb-padctl"
   - Tegra210: "nvidia,tegra210-xusb-padctl"
+  - Tegra186: "nvidia,tegra186-xusb-padctl"
 - reg: Physical base address and length of the controller's registers.
 - resets: Must contain an entry for each entry in reset-names.
 - reset-names: Must include the following entries:
   - "padctl"
 
+For Tegra186:
+- avdd-pll-erefeut-supply: UPHY brick and reference clock as well as UTMI PHY
+  power supply. Must supply 1.8 V.
+- avdd-usb-supply: USB I/Os, VBUS, ID, REXT, D+/D- power supply. Must supply
+  3.3 V.
+- vclamp-usb-supply: Bias rail for USB pad. Must supply 1.8 V.
+- vddio-hsic-supply: HSIC PHY power supply. Must supply 1.2 V.
+
 
 Pad nodes:
 ==========