convolution1d x86 support bf16 storage

[nihui]

No description provided.

[tencent-adm]

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[codecov-commenter]

Codecov Report

❌ Patch coverage is 92.68293% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.34%. Comparing base (2490d63) to head (eb13981).

Files with missing lines	Patch %	Lines
src/layer/x86/convolution1d_x86.cpp	91.42%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6630      +/-   ##
==========================================
- Coverage   93.22%   92.34%   -0.88%     
==========================================
  Files         904      906       +2     
  Lines      283731   286392    +2661     
==========================================
- Hits       264495   264459      -36     
- Misses      19236    21933    +2697     

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