dt-bindings: pse: tps23881: Clarify channels property description

Improve the channels property description to better explain the
relationship between physical delivery channels and PSE PI pairsets.
The previous description was unclear about how channels are referenced
and used in the port matrix mapping.

Signed-off-by: Kory Maincent <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Paolo Abeni <[e-mail]>

Documentation/devicetree/bindings/net/pse-pd/ti,tps23881.yaml

···
     maxItems: 1
 
   channels:
-    description: each set of 8 ports can be assigned to one physical
-      channels or two for PoE4. This parameter describes the configuration
-      of the ports conversion matrix that establishes relationship between
-      the logical ports and the physical channels.
+    description: |
+      Defines the 8 physical delivery channels on the controller that can
+      be referenced by PSE PIs through their "pairsets" property. The actual
+      port matrix mapping is created when PSE PIs reference these channels in
+      their pairsets. For 4-pair operation, two channels from the same group
+      (0-3 or 4-7) must be referenced by a single PSE PI.
     type: object
     additionalProperties: false