[local] Update the importing after platform_fixtures.py is moved

Totally 7 files were affected by PR  sonic-net#1503. One of these
files is local only. This commit is to update the local only
script. Rest of the 6 scriptes were updated in PR sonic-net#1547.

Change-Id: I95a26849b974fbe16d83f8b8cfac4ebd8f95525c

tests/platform/mellanox/test_check_sfp_plug_in_out_sim.py

@@ -7,7 +7,7 @@
 import time
 import pytest
 
-from platform_fixtures import conn_graph_facts
+from common.fixtures.conn_graph_facts import conn_graph_facts
 from check_interface_status import parse_intf_status
 
 ans_host = None