MIPS: Fix improper use of odd FP reg on mips32r6

test/cctest/test-macro-assembler-mips.cc

Index: test/cctest/test-macro-assembler-mips.cc
diff --git a/test/cctest/test-macro-assembler-mips.cc b/test/cctest/test-macro-assembler-mips.cc
index 727b9322c96d2b6e4f0298e7d963fa9e9f82b5d3..c7736314c8c5576894a118dc48df31ef1aaaa048 100644
--- a/test/cctest/test-macro-assembler-mips.cc
+++ b/test/cctest/test-macro-assembler-mips.cc
@@ -525,7 +525,7 @@ TEST(cvt_s_w_Trunc_uw_s) {
     uint32_t input = *i;
     auto fn = [](MacroAssembler* masm) {
       __ cvt_s_w(f0, f4);
-      __ Trunc_uw_s(f2, f0, f1);
+      __ Trunc_uw_s(f2, f0, f6);
     };
     CHECK_EQ(static_cast<float>(input), run_Cvt<uint32_t>(input, fn));
   }