[Mellanox] Read PSU fan max/min speed per PSU (#8563)

#### Why I did it
New PSU could install different type of fan, so fan max/min speed should be read per PSU

#### How I did it
The existing implementation read PSU max/min fan speed from a common file, change it to read from per PSU file

#### How to verify it
Manual test

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

@@ -65,8 +65,8 @@ def __init__(self, fan_index, fan_drawer, position, psu_fan = False, psu=None):
             self.fan_speed_get_path = "psu{}_fan1_speed_get".format(self.index)
             self.fan_presence_path = "psu{}_fan1_speed_get".format(self.index)
             self._name = 'psu{}_fan{}'.format(self.index, 1)
-            self.fan_max_speed_path = os.path.join(CONFIG_PATH, "psu_fan_max")
-            self.fan_min_speed_path = os.path.join(CONFIG_PATH, "psu_fan_min")
+            self.fan_max_speed_path = os.path.join(FAN_PATH, "psu{}_fan_max".format(self.index))
+            self.fan_min_speed_path = os.path.join(FAN_PATH, "psu{}_fan_min".format(self.index))
             self.psu_i2c_bus_path = os.path.join(CONFIG_PATH, 'psu{0}_i2c_bus'.format(self.index))
             self.psu_i2c_addr_path = os.path.join(CONFIG_PATH, 'psu{0}_i2c_addr'.format(self.index))
             self.psu_i2c_command_path = os.path.join(CONFIG_PATH, 'fan_command')