[Mellanox pytest] change the way to check default fan speed setting

tests/platform/mellanox/check_hw_mgmt_service.py

@@ -3,6 +3,7 @@
 """
 import logging
 import re
+import time
 
 from common.utilities import wait_until
 
@@ -20,7 +21,15 @@ def check_hw_management_service(dut):
     """This function is to check the hw management service and related settings.
     """
     logging.info("Check fan speed setting")
-    assert not wait_until_fan_speed_set_to_default(dut), \
+    # In current hw-mgmt implementation, it set the fan speed to default
+    # value when suspending thermal control algorithm, but it takes some time
+    # to take effect. During this period, algorithm could change speed value
+    # back and hw-mgmt will set it to default again, so it's possible that
+    # although at some point the speed value is default but it could be changed
+    # after some time. So we just wait for 300 secs to make sure fan speed is
+    # set to default value instead of check every 10s.
+    time.sleep(300)
+    assert fan_speed_set_to_default(dut), \
         "Fan speed is not default to 60 percent in 5 minutes. 153/255=60%"
 
     logging.info("Check service status using systemctl")