Fixing an issue in which a very slow radio_clk (due to low sample clock
rate) could cause bus transactions to be issued to the timekeeper
faster than it could service them, resulting in a timeout. This change
replaces RegPort with CtrlPort so that proper flow control can be
maintained to the timekeeper.
Original-commit: 2e910c5307702c3f3efb6dc8cb60f4f71ce11e67