memory: fix a bug of detection of memory region collision

memory: fix a bug of detection of memory region collision

The collision reports before and after this patch are:

before:

warning: subregion collision cfc/4 (pci-conf-data) vs cf8/4 (pci-conf-idx)
warning: subregion collision 8000000/f8000000 (pci-hole) vs 0/8000000 (ram-below-4g)
warning: subregion collision 100000000/4000000000000000 (pci-hole64) vs 8000000/f8000000 (pci-hole)
warning: subregion collision 4d1/1 (kvm-elcr) vs 4d0/1 (kvm-elcr)
warning: subregion collision fec00000/1000 (kvm-ioapic) vs 8000000/f8000000 (pci-hole)
warning: subregion collision 80/1 (ioport80) vs 7e/2 (kvmvapic)
warning: subregion collision fed00000/400 (hpet) vs 8000000/f8000000 (pci-hole)
warning: subregion collision 81/3 (dma-page) vs 80/1 (ioport80)
warning: subregion collision 8/8 (dma-cont) vs 0/8 (dma-chan)
warning: subregion collision d0/10 (dma-cont) vs c0/10 (dma-chan)
warning: subregion collision 0/80 (ich9-pm) vs 8/8 (dma-cont)
warning: subregion collision 0/80 (ich9-pm) vs 0/8 (dma-chan)
warning: subregion collision 0/80 (ich9-pm) vs 64/1 (i8042-cmd)
warning: subregion collision 0/80 (ich9-pm) vs 60/1 (i8042-data)
warning: subregion collision 0/80 (ich9-pm) vs 61/1 (elcr)
warning: subregion collision 0/80 (ich9-pm) vs 40/4 (kvm-pit)
warning: subregion collision 0/80 (ich9-pm) vs 70/2 (rtc)
warning: subregion collision 0/80 (ich9-pm) vs 20/2 (kvm-pic)
warning: subregion collision 0/80 (ich9-pm) vs 7e/2 (kvmvapic)
warning: subregion collision 4/2 (acpi-cnt) vs 0/4 (acpi-evt)
warning: subregion collision 30/8 (apci-smi) vs 20/10 (apci-gpe0)
warning: subregion collision b0000000/10000000 (pcie-mmcfg) vs 8000000/f8000000 (pci-hole)

after:

warning: subregion collision fec00000/1000 (kvm-ioapic) vs 8000000/f8000000 (pci-hole)
warning: subregion collision fed00000/400 (hpet) vs 8000000/f8000000 (pci-hole)
warning: subregion collision 0/80 (ich9-pm) vs 8/8 (dma-cont)
warning: subregion collision 0/80 (ich9-pm) vs 0/8 (dma-chan)
warning: subregion collision 0/80 (ich9-pm) vs 64/1 (i8042-cmd)
warning: subregion collision 0/80 (ich9-pm) vs 60/1 (i8042-data)
warning: subregion collision 0/80 (ich9-pm) vs 61/1 (elcr)
warning: subregion collision 0/80 (ich9-pm) vs 40/4 (kvm-pit)
warning: subregion collision 0/80 (ich9-pm) vs 70/2 (rtc)
warning: subregion collision 0/80 (ich9-pm) vs 20/2 (kvm-pic)
warning: subregion collision 0/80 (ich9-pm) vs 7e/2 (kvmvapic)
warning: subregion collision b0000000/10000000 (pcie-mmcfg) vs 8000000/f8000000 (pci-hole)

Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>