Excise functional_init_*

No one was using it. If anyone was indeed using it, I hope they'll
complain loudly.

Author: zou3519

functorch/__init__.py

@@ -17,7 +17,6 @@
     combine_state_for_ensemble,
     FunctionalModule,
 )
-from ._src.make_functional import functional_init, functional_init_with_buffers
 from ._src.python_key import wrap_key, PythonTensor, pythonkey_trace, make_fx, nnc_jit, make_nnc
 from ._src.nnc_compile import nnc_compile, get_ops
 from ._src.eager_compilation import compiled_function, compiled_module, tvm_compile, draw_joint_graph, default_partition, partition_with_recompute_fwd_in_bwd

test/test_eager_transforms.py

@@ -21,6 +21,8 @@
 from functorch import (
     grad, vjp, vmap, jacrev, grad_and_value,
     make_functional, make_functional_with_buffers,
+)
+from functorch._src.make_functional import (
     functional_init, functional_init_with_buffers,
 )
 

test/test_vmap.py

@@ -36,8 +36,9 @@
 import types
 
 import functorch
-from functorch import vmap, functional_init_with_buffers
+from functorch import vmap
 from functorch._C import reshape_dim_into, reshape_dim_outof
+from functorch._src.make_functional import functional_init_with_buffers
 
 FALLBACK_REGEX = 'There is a performance drop'