[snmp] skip psu fans during test_fan_info (#6265)

What is the motivation for this PR?
Submodule update changed fan information in redis database. Changes added 2 psu fans to 4 existing fans to FAN_INFO on Arista platform. According to documentation, FAN_INFO is the source of fan mib entries, PSU_INFO - of psu related entries, meaning tests for checking physical entity mib should be separated for FAN_INFO and PSU_INFO, and PSU entries should not be checked in a fan test (in this case - in test_fan_info)

How did you do it?
I checked handling of psu related entries in another test created for fan mib entries - test_remove_insert_fan_and_check_fan_info. This test skips psu entries:

        if 'PSU' in parent_name:
            continue

How did you verify/test it?
Run snmp/test_snmp_phy_entity.py::test_fan_info

Author: romanvasylys

tests/snmp/test_snmp_phy_entity.py

@@ -277,15 +277,14 @@ def test_fan_info(duthosts, enum_rand_one_per_hwsku_hostname, snmp_physical_enti
         entity_info = redis_hgetall(duthost, STATE_DB, entity_info_key)
         position = int(entity_info['position_in_parent'])
         parent_name = entity_info['parent_name']
-        if parent_name == CHASSIS_KEY:
+        if 'PSU' in parent_name:
+            continue
+        elif parent_name == CHASSIS_KEY:
             parent_oid = MODULE_TYPE_FAN_DRAWER + position * MODULE_INDEX_MULTIPLE
         else:
             parent_entity_info = redis_hgetall(duthost, STATE_DB, PHYSICAL_ENTITY_KEY_TEMPLATE.format(parent_name))
             parent_position = int(parent_entity_info['position_in_parent'])
-            if 'PSU' in parent_name:
-                parent_oid = MODULE_TYPE_PSU + parent_position * MODULE_INDEX_MULTIPLE
-            else:
-                parent_oid = MODULE_TYPE_FAN_DRAWER + parent_position * MODULE_INDEX_MULTIPLE
+            parent_oid = MODULE_TYPE_FAN_DRAWER + parent_position * MODULE_INDEX_MULTIPLE
         expect_oid = parent_oid + DEVICE_TYPE_FAN + position * DEVICE_INDEX_MULTIPLE
         assert expect_oid in snmp_physical_entity_info, 'Cannot find fan {} in physical entity mib'.format(name)
         fan_snmp_fact = snmp_physical_entity_info[expect_oid]