[llvm] AMDGPU: Remove unnecessary reference (PR #162085)

[Matt Arsenault via llvm-commits]

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@@ -541,7 +541,7 @@ unsigned GCNSubtarget::getMaxNumSGPRs(const Function &F) const {
 
 unsigned GCNSubtarget::getBaseMaxNumVGPRs(
     const Function &F, std::pair<unsigned, unsigned> NumVGPRBounds) const {
-  const auto &[Min, Max] = NumVGPRBounds;
+  const auto [Min, Max] = NumVGPRBounds;
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arsenm wrote:

But they're also not mutated. I'd rather just have everything const all the time tbh. 

https://github.com/llvm/llvm-project/pull/162085