Dead code, no longer needed, causes duplicate checkins (project-chip#36051)

* Dead code, no longer needed

* Restyled by clang-format

---------

Co-authored-by: Restyled.io <commits@restyled.io>

Author: woody-apple

src/darwin/Framework/CHIP/MTRDeviceController_XPC.mm

@@ -83,11 +83,6 @@ - (void)_unregisterNodeID:(NSNumber *)nodeID
     [self _updateRegistrationInfo];
 }
 
-- (void)_checkinWithContext:(NSDictionary *)context
-{
-    [self _updateRegistrationInfo];
-}
-
 - (void)removeDevice:(MTRDevice *)device
 {
     [super removeDevice:device];
@@ -253,8 +248,6 @@ - (BOOL)_setupXPCConnection
         MTR_LOG("%@ Activating new XPC connection", self);
         [self.xpcConnection activate];
 
-        [self _checkinWithContext:[NSDictionary dictionary]];
-
         // FIXME: Trying to kick all the MTRDevices attached to this controller to re-establish connections
         //        This state needs to be stored properly and re-established at connnection time