PCI: designware: Make "clocks" and "clock-names" optional DT properties

Move the clock-related properties in the DesignWare PCIe controller
bindings to 'optional' set of properties.

[bhelgaas: move to separate patch]
Signed-off-by: Bhupesh Sharma <bhupesh.sharma@freescale.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>

Documentation/devicetree/bindings/pci/designware-pcie.txt

@@ -14,11 +14,7 @@ Required properties:
 - interrupt-map-mask and interrupt-map: standard PCI properties
 	to define the mapping of the PCIe interface to interrupt
 	numbers.
-- clocks: Must contain an entry for each entry in clock-names.
-	See ../clocks/clock-bindings.txt for details.
-- clock-names: Must include the following entries:
-	- "pcie"
-	- "pcie_bus"
+- num-lanes: number of lanes to use
 
 Optional properties:
 - num-lanes: number of lanes to use (this property should be specified unless
@@ -27,3 +23,8 @@ Optional properties:
 - bus-range: PCI bus numbers covered (it is recommended for new devicetrees to
   specify this property, to keep backwards compatibility a range of 0x00-0xff
   is assumed if not present)
+- clocks: Must contain an entry for each entry in clock-names.
+	See ../clocks/clock-bindings.txt for details.
+- clock-names: Must include the following entries:
+	- "pcie"
+	- "pcie_bus"