Steps to reproduce this bug:
1. virsh attach-disk domain --source diskimage --target sdb --sourcetype file --driver qemu --subdriver qcow2
   error: Failed to attach disk
   error: operation failed: adding scsi-disk,bus=scsi0.0,scsi-id=1,drive=drive-scsi0-0-1,id=scsi0-0-1 device failed: Property 'scsi-disk.drive' can't find value 'drive-scsi0-0-1'
2. service libvirtd restart
   Stopping libvirtd daemon:                                  [  OK  ]
   Starting libvirtd daemon:                                  [  OK  ]
3. virsh attach-disk domain --source diskimage --target sdb --sourcetype file --driver qemu --subdriver raw
   error: Failed to attach disk
   error: operation failed: adding lsi,id=scsi0,bus=pci.0,addr=0x6 device failed: Duplicate ID 'scsi0' for device

The reason is that we create a new scsi controller but we do not update
/var/run/libvirt/qemu/domain.xml.
Signed-off-by: NWen Congyang <wency@cn.fujitsu.com>