Revert "(MTIA) Move "empty_cache" API (#143402)"

This reverts commit c7d9f298072a3f59b39517e367c7d3d2ea30e6d9.

Reverted https://github.com/pytorch/pytorch/pull/143402 on behalf of https://github.com/huydhn due to The internal diff D67148738 has been reverted ([comment](https://github.com/pytorch/pytorch/pull/143402#issuecomment-2557982597))

docs/source/mtia.memory.rst

@@ -10,6 +10,5 @@ The MTIA backend is implemented out of the tree, only interfaces are be defined
     :toctree: generated
     :nosignatures:
 
-    empty_cache
     memory_stats
     max_memory_allocated

torch/mtia/__init__.py

@@ -187,6 +187,11 @@ def get_device_capability(device: Optional[_device_t] = None) -> Tuple[int, int]
     return torch._C._mtia_getDeviceCapability(_get_device_index(device, optional=True))
 
 
+def empty_cache() -> None:
+    r"""Empty the MTIA device cache."""
+    return torch._C._mtia_emptyCache()
+
+
 def set_stream(stream: Stream):
     r"""Set the current stream.This is a wrapper API to set the stream.
         Usage of this function is discouraged in favor of the ``stream``

torch/mtia/memory.py

@@ -10,11 +10,6 @@ from . import _device_t, is_initialized
 from ._utils import _get_device_index
 
 
-def empty_cache() -> None:
-    r"""Empty the MTIA device cache."""
-    return torch._C._mtia_emptyCache()
-
-
 def max_memory_allocated(device: Optional[_device_t] = None) -> int:
     r"""Return the maximum memory allocated in bytes for a given device.
 
@@ -42,7 +37,6 @@ def memory_stats(device: Optional[_device_t] = None) -> Dict[str, Any]:
 
 
 __all__ = [
-    "empty_cache",
     "memory_stats",
     "max_memory_allocated",
 ]