hw/sysbus: Remove unused sysbus_mmio_unmap

The last use of sysbus_mmio_unmap was removed by
  981b1c6266 ("spapr/xive: rework the mapping the KVM memory regions")

Remove it.

Signed-off-by: Dr. David Alan Gilbert <dave@treblig.org>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

hw/core/sysbus.c

@@ -154,16 +154,6 @@ static void sysbus_mmio_map_common(SysBusDevice *dev, int n, hwaddr addr,
     }
 }
 
-void sysbus_mmio_unmap(SysBusDevice *dev, int n)
-{
-    assert(n >= 0 && n < dev->num_mmio);
-
-    if (dev->mmio[n].addr != (hwaddr)-1) {
-        memory_region_del_subregion(get_system_memory(), dev->mmio[n].memory);
-        dev->mmio[n].addr = (hwaddr)-1;
-    }
-}
-
 void sysbus_mmio_map(SysBusDevice *dev, int n, hwaddr addr)
 {
     sysbus_mmio_map_common(dev, n, addr, false, 0);

include/hw/sysbus.h

@@ -82,7 +82,6 @@ qemu_irq sysbus_get_connected_irq(SysBusDevice *dev, int n);
 void sysbus_mmio_map(SysBusDevice *dev, int n, hwaddr addr);
 void sysbus_mmio_map_overlap(SysBusDevice *dev, int n, hwaddr addr,
                              int priority);
-void sysbus_mmio_unmap(SysBusDevice *dev, int n);
 
 bool sysbus_realize(SysBusDevice *dev, Error **errp);
 bool sysbus_realize_and_unref(SysBusDevice *dev, Error **errp);