engine: Fix null dereference in CommandBase by coverity

CID 1062086 (#1 of 1): Dereference null return value (NULL_RETURNS)
null_method_call: Calling a method on null object
getQuotaConsumptionParameters()

Change-Id: I450d48d0840411db44c95fc15b62eb7ab33be91d
Signed-off-by: Moti Asayag <masayag@redhat.com>