hw/net/xilinx_ethlite: Map RESERVED I/O as unimplemented

hw/net/xilinx_ethlite: Map RESERVED I/O as unimplemented

In order to track access to reserved I/O space, use yet
another UnimplementedDevice covering the whole device
memory range. Mapped with lower priority (-1).

The memory flat view becomes:

  (qemu) info mtree -f
  FlatView #0
   Root memory region: system
    0000000081000000-00000000810007e3 (prio 0, ram): ethlite.tx[0]buf
    00000000810007e4-00000000810007f3 (prio 0, i/o): ethlite.mdio
    00000000810007f4-00000000810007ff (prio 0, i/o): ethlite.tx[0]io
    0000000081000800-0000000081000fe3 (prio 0, ram): ethlite.tx[1]buf
    0000000081000fe4-0000000081000ff3 (prio -1, i/o): ethlite.reserved @0000000000000fe4
    0000000081000ff4-0000000081000fff (prio 0, i/o): ethlite.tx[1]io
    0000000081001000-00000000810017e3 (prio 0, ram): ethlite.rx[0]buf
    00000000810017e4-00000000810017fb (prio -1, i/o): ethlite.reserved @00000000000017e4
    00000000810017fc-00000000810017ff (prio 0, i/o): ethlite.rx[0]io
    0000000081001800-0000000081001fe3 (prio 0, ram): ethlite.rx[1]buf
    0000000081001fe4-0000000081001ffb (prio -1, i/o): ethlite.reserved @0000000000001fe4
    0000000081001ffc-0000000081001fff (prio 0, i/o): ethlite.rx[1]io

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20241114210010.34502-20-philmd@linaro.org>