valve inventory item: drop PairName property

Drop the PairName property as per discussion on [1]. This property will
be moved to Valve configuration object in a later patch. There are no
users of this inventory object at the moment so its safe to make this
change.

[1] https://gerrit.openbmc.org/c/openbmc/phosphor-dbus-interfaces/+/77416/comment/baa30f7d_b44b479d/

Change-Id: Iacf91c9c20766d9a6fc0a94d70e5a69b60280387
Signed-off-by: Jagpal Singh Gill <paligill@gmail.com>
diff --git a/schemas/openbmc-dbus.json b/schemas/openbmc-dbus.json
index 8d3f834..0ac456f 100644
--- a/schemas/openbmc-dbus.json
+++ b/schemas/openbmc-dbus.json
@@ -182,13 +182,9 @@
                                         "xyz.openbmc_project.Inventory.Item.Valve.Direction.Return",
                                         "xyz.openbmc_project.Inventory.Item.Valve.Direction.Unknown"
                                     ]
-                                },
-                                "PairName": {
-                                    "description": "This property specifies the pair name for valves when they form a supply and return valve pair; otherwise, it is set to NA.",
-                                    "type": "string"
                                 }
                             },
-                            "required": ["Direction", "PairName"],
+                            "required": ["Direction"],
                             "type": "object"
                         }
                     }