list volumes can not be filtered by bootable

[Yiling Qin]

the ‘bootable’ filter of volume list is ineffective when ‘bootable’ is set to be false.

[chenwei (chenwei110)]

[root@test ~]# cinder list --filters bootable=False
+--------------------------------------+-----------+------------------------------------------------+------+-------------+----------+--------------------------------------+
| ID | Status | Name | Size | Volume Type | Bootable | Attached to |
+--------------------------------------+-----------+------------------------------------------------+------+-------------+----------+--------------------------------------+
| 051dbf74-34d0-4850-8cd2-c2ade2fafce3 | available | b01f2a70-c686-44ea-b767-c241822f4620-blank-vol | 40 | __DEFAULT__ | false | |