using PyTorch WARP_SHFL_DOWN macro for half support

[zstreet87]

Motivation

In preparation for ROCm5.6, this is required for successful compilation. Using AMD's intrinsic resulted in an "ambiguous-type" error. TLDR; some hip-header migration it seems.

This PR will require tests against ROCm5.6 once it is released and the CI is using it.

Modification

Using Pytorch's macro to handle the shfl_down intrinsic for functionality and portability.

Checklist

Before PR:

• I have read and followed the workflow indicated in the CONTRIBUTING.md to create this PR.
• Pre-commit or linting tools indicated in CONTRIBUTING.md are used to fix the potential lint issues.
• Bug fixes are covered by unit tests, the case that causes the bug should be added in the unit tests.
• New functionalities are covered by complete unit tests. If not, please add more unit test to ensure the correctness.
• The documentation has been modified accordingly, including docstring or example tutorials.

After PR:

• If the modification has potential influence on downstream or other related projects, this PR should be tested with some of those projects, like MMDet or MMCls.
• CLA has been signed and all committers have signed the CLA in this PR.

[zstreet87]

May I have an ETA for the CI to complete? I appreciate it!

[zstreet87]

We are needing this for rocm

[zstreet87]

@grimoire can you take a look please?

[grimoire]

LGTM @zhouzaida

[zstreet87]

thanks @grimoire!

Anyone else, please review

[zstreet87]

@zhouzaida can you take a look please?

[zhouzaida]

@zhouzaida can you take a look please?

Hi @zstreet87 , sorry for my late reply.