dt-bindings: net: ti,dp83869: Drop value on boolean 'ti,max-output-impedance'

DT booleans don't have a value and 'ti,max-output-impedance' is defined and
used as a boolean. So drop the bogus value in the example.
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220107030513.2385482-1-robh@kernel.org

Documentation/devicetree/bindings/net/ti,dp83869.yaml

@@ -92,7 +92,7 @@ examples:
         tx-fifo-depth = <DP83869_PHYCR_FIFO_DEPTH_4_B_NIB>;
         rx-fifo-depth = <DP83869_PHYCR_FIFO_DEPTH_4_B_NIB>;
         ti,op-mode = <DP83869_RGMII_COPPER_ETHERNET>;
-        ti,max-output-impedance = "true";
+        ti,max-output-impedance;
         ti,clk-output-sel = <DP83869_CLK_O_SEL_CHN_A_RCLK>;
         rx-internal-delay-ps = <2000>;
         tx-internal-delay-ps = <2000>;