Remove device count cache when import monai (#7581)

workaround for #7575


### Types of changes
<!--- Put an `x` in all the boxes that apply, and remove the not
applicable items -->
- [x] Non-breaking change (fix or new feature that would not break
existing functionality).
- [ ] Breaking change (fix or new feature that would cause existing
functionality to change).
- [ ] New tests added to cover the changes.
- [ ] Integration tests passed locally by running `./runtests.sh -f -u
--net --coverage`.
- [ ] Quick tests passed locally by running `./runtests.sh --quick
--unittests --disttests`.
- [ ] In-line docstrings updated.
- [ ] Documentation updated, tested `make html` command in the `docs/`
folder.

---------

Signed-off-by: YunLiu <55491388+KumoLiu@users.noreply.github.com>
Co-authored-by: Eric Kerfoot <17726042+ericspod@users.noreply.github.com>

monai/__init__.py

@@ -83,6 +83,11 @@
     from .utils.tf32 import detect_default_tf32
 
     detect_default_tf32()
+    import torch
+
+    # workaround related to https://github.com/Project-MONAI/MONAI/issues/7575
+    if hasattr(torch.cuda.device_count, "cache_clear"):
+        torch.cuda.device_count.cache_clear()
 except BaseException:
     from .utils.misc import MONAIEnvVars