[llvm] [RISCV] Rename some DecoderNamespaces and cleanup debug messages. NFC (PR #131409)

[Alex Bradbury via llvm-commits]

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@@ -690,12 +690,10 @@ static constexpr DecoderListEntry DecoderList32[]{
     {DecoderTableXCV32, XCVFeatureGroup, "CORE-V extensions"},
     {DecoderTableXqci32, XqciFeatureGroup, "Qualcomm uC Extensions"},
     {DecoderTableXRivos32, XRivosFeatureGroup, "Rivos"},
-    {DecoderTable32, {}, "RISCV32"},
-    {DecoderTableRV32GPRPair32, {}, "RV32GPRPair (rv32 and GPR pairs)"},
+    {DecoderTable32, {}, "standard 32-bit instructions"},
+    {DecoderTableRV32Only32, {}, "RV32-only standard instructions"},
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asb wrote:

To match the line above, perhaps it should read "RV32-only standard 32-bit instructions"

https://github.com/llvm/llvm-project/pull/131409