dt-bindings: net: Add IEP property in ICSSG

Add IEP property in ICSSG hardware DT binding document.
ICSSG uses IEP (Industrial Ethernet Peripheral) to support timestamping
of ethernet packets, PTP and PPS.
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Roger Quadros <rogerq@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: MD Danish Anwar <danishanwar@ti.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/ti,icssg-prueth.yaml

@@ -52,6 +52,14 @@ properties:
     description:
       phandle to MII_RT module's syscon regmap
 
+  ti,iep:
+    $ref: /schemas/types.yaml#/definitions/phandle-array
+    maxItems: 2
+    items:
+      maxItems: 1
+    description:
+      phandle to IEP (Industrial Ethernet Peripheral) for ICSSG
+
   interrupts:
     maxItems: 2
     description:
@@ -155,6 +163,7 @@ examples:
                     "tx1-0", "tx1-1", "tx1-2", "tx1-3",
                     "rx0", "rx1";
         ti,mii-g-rt = <&icssg2_mii_g_rt>;
+        ti,iep = <&icssg2_iep0>, <&icssg2_iep1>;
         interrupt-parent = <&icssg2_intc>;
         interrupts = <24 0 2>, <25 1 3>;
         interrupt-names = "tx_ts0", "tx_ts1";