AXI interface hangs when given both AWVALID and AWREADY

[ZipCPU]

See https://github.com/jofrfu/tinyTPU/blob/b8df109e7bf1c358e89dee7fbf9cc0d65786b6fb/src/vhdl/AXI/tinyTPU_v1_0_S00_AXI.vhd#L353-L366

If both AWVALID and AWREADY are true on the same clock, the design should pick one, and come back later to handle the other.