Made a few more changes to the axi read interface.
Made a few more changes to the axi read interface.

andrewandrepowell/axiplasma,andrewandrepowell/kernel-on-chip,andrewandrepowell/kernel-on-chip,andrewandrepowell/axiplasma,andrewandrepowell/axiplasma,andrewandrepowell/axiplasma