dialects: Fix inline_asm unitattrs to not be properties

[JosseVanDelm]

@superlopuh pointed out that #2203 contains an erroneous implementation of a UnitAttr being implemented as properties. This is incorrect, since upstream prints the UnitAttrs as attributes and properties.
It was a bit confusing because some other ops in the LLVM dialect have the same mistake right now.
This happens under the radar because in testing, properties are printed as attributes.
This PR fixes the inline_asm operation.

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (ad8f2e0) 89.47% compared to head (da681b2) 89.48%.

Files	Patch %	Lines
xdsl/dialects/llvm.py	66.66%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2223   +/-   ##
=======================================
  Coverage   89.47%   89.48%           
=======================================
  Files         326      326           
  Lines       38828    38825    -3     
  Branches     5746     5744    -2     
=======================================
  Hits        34741    34741           
+ Misses       3289     3286    -3     
  Partials      798      798           

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[superlopuh]

thank you!