MSimNetworkController: disable CHATTY logs

Change-Id: Ic9dd166aa6ac77647dc69acea31d2ebde3a87f0a
MSimNetworkController: Quiet logspam

* Most uses of Slog.d are not protected by the if (DEBUG) they should
  be. Make it so.

Change-Id: I36151113b1bfcdbe84c27abf39918441e23a8e88