On the Alpha DP264 machine, the Cirrus VGA is I/O mapped
in the 3C0H-3CFH range, thus I/O base used by the parallel
device clashes, and since a4cb7739 the VGA is not
working:

(qemu) info mtree
address-space: memory
  0000000000000000-ffffffffffffffff (prio 0, i/o): system
    00000801fc000000-00000801fdffffff (prio 0, i/o): pci0-io
      ...
      00000801fc0003b4-00000801fc0003b5 (prio 0, i/o): vga
      00000801fc0003ba-00000801fc0003ba (prio 0, i/o): vga
      00000801fc0003bc-00000801fc0003c3 (prio 0, i/o): parallel
                                    ^^^                ^^^^^^^^
      00000801fc0003c0-00000801fc0003cf (prio 0, i/o): vga
                   ^^^
      00000801fc0003d4-00000801fc0003d5 (prio 0, i/o): vga
      00000801fc0003da-00000801fc0003da (prio 0, i/o): vga
      ...

As there is no particular reason to use this base address
(introduced in 7bea0dd4), change to 378H which is the
default on PC machines.

Reported-by: Emilio G. Cota <cota@braap.org>
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Tested-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20180614233935.26585-1-f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>