fix test_buffer_deployment case NoneType issue#6050

wangxin merged 1 commit intosonic-net:mastersonic-net/sonic-mgmt:masterfrom

lipxu:20220726_14689836_test_buffer_deploymentlipxu/sonic-mgmt-lipxu-fork:20220726_14689836_test_buffer_deploymentCopy head branch name to clipboard