merged changes in axis

lib/axis/COPYING

lib/axis/rtl/arbiter.v

lib/axis/rtl/axis_adapter.v

lib/axis/rtl/axis_arb_mux_4.v

lib/axis/rtl/axis_async_fifo.v

lib/axis/rtl/axis_async_frame_fifo.v

lib/axis/rtl/axis_cobs_decode.v

lib/axis/rtl/axis_cobs_encode.v

lib/axis/rtl/axis_crosspoint_4x4.v

lib/axis/rtl/axis_demux_4.v

lib/axis/rtl/axis_fifo.v

lib/axis/rtl/axis_frame_fifo.v

lib/axis/rtl/axis_frame_join_4.v

lib/axis/rtl/axis_frame_length_adjust.v

lib/axis/rtl/axis_frame_length_adjust_fifo.v

lib/axis/rtl/axis_ll_bridge.v

lib/axis/rtl/axis_mux_4.v

lib/axis/rtl/axis_rate_limit.v

lib/axis/rtl/axis_register.v

lib/axis/rtl/axis_srl_fifo.v