If we set mountpoints to qmp_guest_fsfreeze_freeze_list,
we may got nothing to freeze as all mountpoints are
not valid.
So call ga_unset_frozen in this senario.
Also, if we return 0 frozen fs, there is no need to call
guest-fsfreeze-thaw.
Cc: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Chen Hanxiao <chenhanxiao@gmail.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>