Use copy instead of dataWithData

Author: ksperling-apple

src/darwin/Framework/CHIP/MTROperationalCredentialsDelegate.mm

@@ -64,10 +64,8 @@
 
     // Make copies of the certificates, just in case the API consumer
     // has them as MutableData.
-    mRootCert = [NSData dataWithData:rootCert];
-    if (icaCert != nil) {
-        mIntermediateCert = [NSData dataWithData:icaCert];
-    }
+    mRootCert = [rootCert copy];
+    mIntermediateCert = [icaCert copy];
 
     return CHIP_NO_ERROR;
 }