pc87312: Avoid define conflict on mingw32

pc87312: Avoid define conflict on mingw32

Mingw32 headers define FAR, causing this warning:
/src/qemu/hw/pc87312.c:38:0: warning: "FAR" redefined [enabled by default]
In file included from /usr/local/lib/gcc/i686-mingw32msvc/4.7.0/../../../../i686-mingw32msvc/include/windows.h:48:0,
                 from /src/qemu/include/sysemu/os-win32.h:29,
                 from /src/qemu/include/qemu-common.h:46,
                 from /src/qemu/include/exec/ioport.h:27,
                 from /src/qemu/hw/isa.h:6,
                 from /src/qemu/hw/pc87312.h:28,
                 from /src/qemu/hw/pc87312.c:26:
/usr/local/lib/gcc/i686-mingw32msvc/4.7.0/../../../../i686-mingw32msvc/include/windef.h:34:0: note: this is the location of the previous definition

Avoid the warning by expanding the macros.

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Acked-by: Hervé Poussineau <hpoussin@reactos.org>
Signed-off-by: Andreas Färber <andreas.faerber@web.de>