Disable gradient calculation in _check_valid_rotation_matrix()

Summary:
# Make `transform3d.py` a little bit better (performance and code quality)

## 1. Add decorator `torch.no_grad()` to the function `_check_valid_rotation_matrix()`

Function `_check_valid_rotation_matrix()` is needed to identify errors during forward pass only, it's not used for gradients.

## 2. Replace two calls `to` with the single one

Reviewed By: bottler

Differential Revision: D29656501

fbshipit-source-id: 4419e24dbf436c1b60abf77bda4376fb87a593be

Author: Alexey Sidnev

pytorch3d/transforms/transform3d.py

@@ -566,7 +566,7 @@ def __init__(
         if R.shape[-2:] != (3, 3):
             msg = "R must have shape (3, 3) or (N, 3, 3); got %s"
             raise ValueError(msg % repr(R.shape))
-        R = R.to(dtype=dtype).to(device=device_)
+        R = R.to(device=device_, dtype=dtype)
         _check_valid_rotation_matrix(R, tol=orthogonal_tol)
         N = R.shape[0]
         mat = torch.eye(4, dtype=dtype, device=device_)
@@ -752,6 +752,9 @@ def _broadcast_bmm(a, b):
     return a.bmm(b)
 
 
+# pyre-fixme[56]: Decorator `torch.no_grad(...)` could not be called, because
+#  its type `no_grad` is not callable.
+@torch.no_grad()
 def _check_valid_rotation_matrix(R, tol: float = 1e-7):
     """
     Determine if R is a valid rotation matrix by checking it satisfies the