Вы можете использовать понимание списка:
input_list = [{'mac': '', 'location': '801'},
{'mac': 'E464EECBA5EB', 'location': '816'},
{'mac': '', 'location': '817'},
{'mac': 'DCE83F3BC820', 'location': '818'},
{'mac': 'GH12TY674RF1', 'location': ''},
{'mac': 'DCE83F3BC820', 'location': '820'}]
expected_output = [d for d in input_list if all(d.values())]
Вывод:
[{'mac': 'E464EECBA5EB', 'location': '816'},
{'mac': 'DCE83F3BC820', 'location': '818'},
{'mac': 'DCE83F3BC820', 'location': '820'}]