Fix error log while creating PSU thermal object (sonic-net#17789)

- Why I did it
If a PSU is not present, there could be error log while restarting psud or thermalctld:

Jan  8 17:15:52.689616 sonic ERR pmon#psud: Thermal sysfs /run/hw-management/thermal/psu2_temp1_max does not exist

Jan  8 17:15:57.747723 sonic ERR pmon#thermalctld: Thermal sysfs /run/hw-management/thermal/psu2_temp1 does not exist

- How I did it
if a PSU is not present, we should not check the PSU temperature sysfs.

platform/mellanox/mlnx-platform-api/sonic_platform/thermal.py

@@ -220,15 +220,15 @@ def create_indexable_thermal(rule, index, sysfs_folder, position, presence_cb=No
     name = rule['name'].format(index)
     sysfs_folder = rule.get('sysfs_folder', sysfs_folder)
     temp_file = os.path.join(sysfs_folder, rule['temperature'].format(index))
-    _check_thermal_sysfs_existence(temp_file)
+    _check_thermal_sysfs_existence(temp_file, presence_cb)
     if 'high_threshold' in rule:
         high_th_file = os.path.join(sysfs_folder, rule['high_threshold'].format(index))
-        _check_thermal_sysfs_existence(high_th_file)
+        _check_thermal_sysfs_existence(high_th_file, presence_cb)
     else:
         high_th_file = None
     if 'high_critical_threshold' in rule:
         high_crit_th_file = os.path.join(sysfs_folder, rule['high_critical_threshold'].format(index))
-        _check_thermal_sysfs_existence(high_crit_th_file)
+        _check_thermal_sysfs_existence(high_crit_th_file, presence_cb)
     else:
         high_crit_th_file = None
     high_th_default = rule.get('high_threshold_default')
@@ -253,15 +253,15 @@ def create_single_thermal(rule, sysfs_folder, position, presence_cb=None):
 
     sysfs_folder = rule.get('sysfs_folder', sysfs_folder)
     temp_file = os.path.join(sysfs_folder, temp_file)
-    _check_thermal_sysfs_existence(temp_file)
+    _check_thermal_sysfs_existence(temp_file, presence_cb)
     if 'high_threshold' in rule:
         high_th_file = os.path.join(sysfs_folder, rule['high_threshold'])
-        _check_thermal_sysfs_existence(high_th_file)
+        _check_thermal_sysfs_existence(high_th_file, presence_cb)
     else:
         high_th_file = None
     if 'high_critical_threshold' in rule:
         high_crit_th_file = os.path.join(sysfs_folder, rule['high_critical_threshold'])
-        _check_thermal_sysfs_existence(high_crit_th_file)
+        _check_thermal_sysfs_existence(high_crit_th_file, presence_cb)
     else:
         high_crit_th_file = None
     high_th_default = rule.get('high_threshold_default')
@@ -274,7 +274,11 @@ def create_single_thermal(rule, sysfs_folder, position, presence_cb=None):
         return RemovableThermal(name, temp_file, high_th_file, high_crit_th_file, high_th_default, high_crit_th_default, scale, position, presence_cb)
 
 
-def _check_thermal_sysfs_existence(file_path):
+def _check_thermal_sysfs_existence(file_path, presence_cb):
+    if presence_cb:
+        status, _ = presence_cb()
+        if not status:
+            return
     if not os.path.exists(file_path):
         logger.log_error('Thermal sysfs {} does not exist'.format(file_path))