PCI: tegra: Add Tegra 30 PCIe support

Introduce a data structure to parameterize the driver according to SoC
generation, add Tegra30 specific code and update the device tree binding
document for Tegra30 support.
Signed-off-by: Jay Agarwal <jagarwal@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>

Documentation/devicetree/bindings/pci/nvidia,tegra20-pcie.txt

 NVIDIA Tegra PCIe controller
 
 Required properties:
-- compatible: "nvidia,tegra20-pcie"
+- compatible: "nvidia,tegra20-pcie" or "nvidia,tegra30-pcie"
 - device_type: Must be "pci"
 - reg: A list of physical base address and length for each set of controller
   registers. Must contain an entry for each entry in the reg-names property.
@@ -16,6 +16,7 @@ Required properties:
   "msi": The Tegra interrupt that is asserted when an MSI is received
 - pex-clk-supply: Supply voltage for internal reference clock
 - vdd-supply: Power supply for controller (1.05V)
+- avdd-supply: Power supply for controller (1.05V) (not required for Tegra20)
 - bus-range: Range of bus numbers associated with this controller
 - #address-cells: Address representation for root ports (must be 3)
   - cell 0 specifies the bus and device numbers of the root port:
@@ -48,6 +49,7 @@ Required properties:
   "afi": The Tegra clock of that name
   "pcie_xclk": The Tegra clock of that name
   "pll_e": The Tegra clock of that name
+  "cml": The Tegra clock of that name (not required for Tegra20)
 
 Root ports are defined as subnodes of the PCIe controller node.