wsman-epr: fix possible NULL dereferencing
wsman-epr: fix possible NULL dereferencing

Check for NULL from:
ws_xml_find_node_attr
u_strdup
u_malloc
u_parse_query
hash_create2

Replace u_malloc with u_zalloc

Signed-off-by: Alexander Usyskin <2c2d03d7dae842f113743879f565d486184f22a3@intel.com>
Signed-off-by: Vitaly Lubart <b0730d993d30ba92bb2c43417ba30474e8debbf3@intel.com>
Signed-off-by: Tomas Winkler <002a8af089113a6510dbc00453be711ac350fd80@intel.com>

Openwsman/openwsman,vcrhonek/openwsman,vcrhonek/openwsman,kkaempf/openwsman,vcrhonek/openwsman,kkaempf/openwsman,vcrhonek/openwsman,kkaempf/openwsman,Openwsman/openwsman,vcrhonek/openwsman,kkaempf/openwsman,Openwsman/openwsman,Openwsman/openwsman,vcrhonek/openwsman,kkaempf/openwsman,Openwsman/openwsman,Openwsman/openwsman,kkaempf/openwsman,kkaempf/openwsman,Openwsman/openwsman,vcrhonek/openwsman