virtio: run drivers in 32bit mode

virtio version 1.0 registers can (and actually do in the qemu
implementation) live in mmio space.  So we must run the blk and
scsi virtio drivers in 32bit mode, otherwise we can't access them.

This also allows to drop a bunch of GET_LOWFLAT calls from the virtio
code in the following patches.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
diff --git a/Makefile b/Makefile
index f97b1bd..e287530 100644
--- a/Makefile
+++ b/Makefile
@@ -34,7 +34,6 @@
     hw/usb.c hw/usb-uhci.c hw/usb-ohci.c hw/usb-ehci.c \
     hw/usb-hid.c hw/usb-msc.c hw/usb-uas.c \
     hw/blockcmd.c hw/floppy.c hw/ata.c hw/ramdisk.c \
-    hw/virtio-ring.c hw/virtio-pci.c hw/virtio-blk.c hw/virtio-scsi.c \
     hw/lsi-scsi.c hw/esp-scsi.c hw/megasas.c
 SRC16=$(SRCBOTH)
 SRC32FLAT=$(SRCBOTH) post.c memmap.c malloc.c romfile.c x86.c optionroms.c \
@@ -43,6 +42,7 @@
     fw/coreboot.c fw/lzmadecode.c fw/multiboot.c fw/csm.c fw/biostables.c \
     fw/paravirt.c fw/shadow.c fw/pciinit.c fw/smm.c fw/smp.c fw/mtrr.c fw/xen.c \
     fw/acpi.c fw/mptable.c fw/pirtable.c fw/smbios.c fw/romfile_loader.c \
+    hw/virtio-ring.c hw/virtio-pci.c hw/virtio-blk.c hw/virtio-scsi.c \
     hw/tpm_drivers.c
 SRC32SEG=string.c output.c pcibios.c apm.c stacks.c hw/pci.c hw/serialio.c
 DIRS=src src/hw src/fw vgasrc