convolution1d x86 support bf16 storage

[nihui]

No description provided.

[tencent-adm]

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[codecov-commenter]

Codecov Report

❌ Patch coverage is 94.87179% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.79%. Comparing base (2490d63) to head (693bd53).
⚠️ Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
src/layer/x86/convolution1d_x86.cpp	94.28%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6630      +/-   ##
==========================================
+ Coverage   93.22%   93.79%   +0.57%     
==========================================
  Files         904      911       +7     
  Lines      283731   288617    +4886     
==========================================
+ Hits       264495   270703    +6208     
+ Misses      19236    17914    -1322     

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