[JIT] fix freezing with mkldnn tensors

[eellison]

We were accessing their storage which will throw

[facebook-github-bot]

💊 CI failures summary and remediations

As of commit 4413968 (more details on the Dr. CI page):

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• 1/1 failures possibly* introduced in this PR
  • 1/1 non-scanned failure(s)

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[Krovatkin]

[facebook-github-bot]

@eellison has imported this pull request. If you are a Facebook employee, you can view this diff on Phabricator.

[codecov]

Codecov Report

Merging #54632 (4413968) into master (ee73c75) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master   #54632   +/-   ##
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  Coverage   77.41%   77.41%           
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  Files        1893     1893           
  Lines      186226   186231    +5     
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+ Hits       144159   144169   +10     
+ Misses      42067    42062    -5     

[facebook-github-bot]

@eellison merged this pull request in 63997db.

[xsacha]

Saving a frozen MKL is still not working for me in latest nightly.
I get a different error now:
NotImplementedError: Cannot access storage of OpaqueTensorImpl

[eellison]

@xsacha i dont think saving and loading mkldnn tensors work on JIT without freezing, this was just fixing a freezing error. but agreed that it would be nice to fix that. Do you mind opening an issue ?

[xsacha]

I can save a JIT mkldnn model without freezing, but when performing the freeze beforehand and then trying to save I get that error.
Prior to this commit I couldn't do the freeze.