qemu: Error prompt when managed save a shutoff domain

qemu: Error prompt when managed save a shutoff domain

The problem was introduced by commit 4303c91, which removed the checking
of domain state, this patch is to fix it.

Otherwise, improper error will be thrown, e.g.

error: Failed to save domain rhel6 state
error: cannot resolve symlink /var/lib/libvirt/qemu/save/rhel6.save: No such
file or directory