dt-bindings: phy: qmp: Add output-clock-names

The PHY outputs a clock that will act as the parent for
the PHY's pipe clock. Add the name of this clock to the
lane's DT node.

Acked-by: Rob Herring <[e-mail]>
Signed-off-by: Varadarajan Narayanan <[e-mail]>
Signed-off-by: Kishon Vijay Abraham I <[e-mail]>

Documentation/devicetree/bindings/phy/qcom-qmp-phy.txt

···
 	   one for each entry in clock-names.
  - clock-names: Must contain following for pcie and usb qmp phys:
 		 "pipe<lane-number>" for pipe clock specific to each lane.
+ - clock-output-names: Name of the PHY clock that will be the parent for
+		       the above pipe clock.
 
  - resets: a list of phandles and reset controller specifier pairs,
 	   one for each entry in reset-names.
···
 
 			clocks = <&gcc GCC_PCIE_0_PIPE_CLK>;
 			clock-names = "pipe0";
+			clock-output-names = "pcie_0_pipe_clk_src";
 			resets = <&gcc GCC_PCIE_0_PHY_BCR>;
 			reset-names = "lane0";
 		};