[SPARC] Implement L and H inline asm argument modifiers (#87259)

This adds support for using the L and H argument modifiers for twinword
operands in inline asm code, such as in:

```
%1 = tail call i64 asm sideeffect "rd %pc, ${0:L} ; srlx ${0:L}, 32, ${0:H}", "={o4}"()
```

This is needed by the Linux kernel.