Saswell C16: allow temperature to go full range in all modes.

The thermostat seems to auto-switch to anti-freeze mode when turned down, which
is surprising to the user when it cannot be turned back up. Hopefully it can
auto-switch when turning up also.

custom_components/tuya_local/devices/saswell_c16_thermostat.yaml

@@ -13,12 +13,6 @@ primary_entity:
       mapping:
         - scale: 10
           step: 5
-          constraint: preset_mode
-          conditions:
-            - dps_val: "Anti_frozen"
-              range:
-                min: 50
-                max: 150
     - id: 3
       name: preset_mode
       type: string

tests/devices/test_saswell_c16_thermostat.py

@@ -83,8 +83,6 @@ class TestSaswellC16Thermostat(TuyaDeviceTestCase):
 
     def test_maximum_target_temperature(self):
         self.assertEqual(self.subject.max_temp, 40.0)
-        self.dps[PRESET_DPS] = "Anti_frozen"
-        self.assertEqual(self.subject.max_temp, 15.0)
 
     async def test_set_target_temperature(self):
         async with assert_device_properties_set(