Fix: crmd: make node_state erase correctly

This patch fixes the issue on which __guest02__ of "UNCLEAN (offline)" state is not set to OFFLINE by 'stonith_admin -C __GUEST02__'.

 * (1) STONITH failed
```
$ cat /var/log/ha-log
Mar 31 14:52:03 guest01 crmd[29181]:   notice: too_many_st_failures: Too many failures to fence guest02 (11), giving up
```
 * (2) I stopped guest02, and performed stonith_admin.
```
$ crm_mon

Node guest02 (3232261520): UNCLEAN (offline)
Online: [ guest01 ]

```
```
$ stonith_admin -C GUEST02 ; echo $?
0

$ cat /var/log/ha-log
Mar 31 14:52:46 guest01 crmd[22906]:     info: erase_status_tag: Deleting xpath: //node_state[@uname='GUEST02']/lrm
Mar 31 14:52:46 guest01 crmd[22906]:     info: erase_status_tag: Deleting xpath: //node_state[@uname='GUEST02']/transient_attributes
```
 * However, since crmd tried to erase "//node_state[@uname='__GUEST02__']" (xpath) at this time, node_state of __guest02__ remains.
```
$ cibadmin -Q

  <node_state id="3232261520" uname="guest02" in_ccm="false" crmd="offline" crm-debug-origin="post_cache_update" join="member" expected="member">
    <transient_attributes id="3232261520">

```