virStorageBackendLogicalDeleteVol() could not remove the lv with error
"could not remove open logical volume" sometimes. Generally it's caused
by the volume is still active, even if lvremove tries to remove it with
option "--force".

This patch is to fix it by disbale the lv first using "lvchange -aln"
and "lvremove -f" afterwards if the direct "lvremove -f" failed.