Cleanup DeviceInterface in triton test (#152409)

- Remove inherited functions
- Return valid device_count (1 device: idx=0)
- Remove unused function `triton_supported`

Followup to #144399

Pull Request resolved: https://github.com/pytorch/pytorch/pull/152409
Approved by: https://github.com/jansel

test/inductor/extension_backends/triton/device_interface.py

@@ -76,7 +76,7 @@ class DeviceInterface(device_interface.DeviceInterface):
 
     @staticmethod
     def device_count() -> int:
-        raise NotImplementedError
+        return 1
 
     @staticmethod
     def maybe_exchange_device(device: int) -> int:
@@ -92,14 +92,6 @@ class DeviceInterface(device_interface.DeviceInterface):
         ), f"Only device index 0 is supported, tried to set index to {device}"
         return 0  # previous device is always 0
 
-    @staticmethod
-    def current_stream():
-        raise NotImplementedError
-
-    @staticmethod
-    def set_stream(stream) -> None:
-        raise NotImplementedError
-
     @staticmethod
     def get_raw_stream(device_index: int):
         return None
@@ -108,10 +100,6 @@ class DeviceInterface(device_interface.DeviceInterface):
     def synchronize(device) -> None:
         pass
 
-    @classmethod
-    def get_device_properties(cls, device=None) -> DeviceProperties:
-        return cls.Worker.get_device_properties(device)
-
     # Can be mock patched by @patch decorator.
     @staticmethod
     def is_available() -> bool:
@@ -120,7 +108,3 @@ class DeviceInterface(device_interface.DeviceInterface):
     @staticmethod
     def get_compute_capability(device) -> int:
         return 0
-
-    @staticmethod
-    def triton_supported() -> bool:
-        return True