[Enhance] Adapt test cases on Ascend NPU.

[Ginray]

Motivation

The current test case is only compatible with cpu and cuda devices, and an error will be reported when testing on the Ascend NPU.
AssertionError: The values for attribute 'device' do not match: npu:0 != cpu.

Modification

Replace the original 'torch.cuda.is_available()' function with the 'get_device' function.

BC-breaking (Optional)

Does not affect.

Use cases (Optional)

We have passed all 637 test cases of mmpretrain on Ascend npu.

Checklist

Before PR:

• [√] Pre-commit or other linting tools are used to fix the potential lint issues.
• [√] Bug fixes are fully covered by unit tests, the case that causes the bug should be added in the unit tests.
• [√] The modification is covered by complete unit tests. If not, please add more unit test to ensure the correctness.
• [√] The documentation has been modified accordingly, like docstring or example tutorials.

After PR:

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

[codecov]

Codecov Report

Patch coverage: 57.48% and project coverage change: -19.70% ⚠️

Comparison is base (89eaa92) 85.22% compared to head (ef432b3) 65.52%.
Report is 85 commits behind head on main.

❗ Current head ef432b3 differs from pull request most recent head 5a17227. Consider uploading reports for the commit 5a17227 to get more accurate results

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #1728       +/-   ##
===========================================
- Coverage   85.22%   65.52%   -19.70%     
===========================================
  Files         229      330      +101     
  Lines       17243    25671     +8428     
  Branches     2707     4088     +1381     
===========================================
+ Hits        14696    16822     +2126     
- Misses       2046     8233     +6187     
- Partials      501      616      +115     

Flag	Coverage Δ
unittests	65.52% <57.48%> (-19.70%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
mmpretrain/apis/image_retrieval.py	21.42% <19.04%> (+0.88%)	⬆️
mmpretrain/apis/image_caption.py	30.64% <30.64%> (ø)
mmpretrain/apis/feature_extractor.py	37.50% <40.00%> (+0.18%)	⬆️
mmpretrain/apis/model.py	75.65% <65.90%> (-4.02%)	⬇️
mmpretrain/apis/base.py	72.44% <72.44%> (ø)
mmpretrain/__init__.py	100.00% <100.00%> (ø)
mmpretrain/apis/__init__.py	100.00% <100.00%> (ø)
mmpretrain/apis/image_classification.py	86.48% <100.00%> (+0.93%)	⬆️

... and 149 files with indirect coverage changes

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