[llvm] [StackMaps] Check both subregs and superregs for getDwarfRegNum (PR #95837)

[Kai Luo via llvm-commits]

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@@ -1,4 +1,4 @@
-; RUN: llc -verify-machineinstrs < %s | FileCheck %s
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bzEq wrote:

Maybe add another `RUN` for `pwr10`, not update this one.

https://github.com/llvm/llvm-project/pull/95837