The clock crossing of the ctrlport used FIFOs to transfer requests and responses
between clock domains. This commit adds a handshake based on the pulse
synchronizer to reduce the resource usage for ctrlport clock domain crossing.
Data is stored in a single register while the pulse synchronizer handles the
signaling of valid flags.
Original-commit: 2c2bb3a0b7269dcbd8b5933ce1c0c29ca17f599d
