[llvm] X86: Fix asserting on bfloat argument/return without sse2 (PR #93146)

[Matt Arsenault via llvm-commits]

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@@ -811,8 +854,7 @@ define void @store_bfloat(ptr %fptr, bfloat %v) {
   ret void
 }
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arsenm wrote:

It's ABI promotes to float vs. ABI promotes to i16 

https://github.com/llvm/llvm-project/pull/93146