Fix value for query_key_map['disk'] in method DecortController.rg_update: 'CU_D' -> 'CU_DM'

module_utils/decort_utils.py

@@ -1839,7 +1839,7 @@ class DecortController(object):
         # - when quering resource limits, the keys are in the form of cloud units (CU_*)
         query_key_map = dict(cpu='CU_C',
                              ram='CU_M',
-                             disk='CU_D',
+                             disk='CU_DM',
                              ext_ips='CU_I', 
                              net_transfer='CU_NP',)
         set_key_map = dict(cpu='maxCPUCapacity',