arch,cpu,sim: Store registers in InstRecord with InstResult.

The InstResult knows how to print registers without having to know about
their actual types.

Change-Id: Ib858e32a7b2fabbde4857165b9e88e87294942c8
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/50254
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Gabe Black <gabe.black@gmail.com>

src/arch/mips/isa/formats/fp.isa

@@ -109,7 +109,7 @@ output exec {{
             if (isNan(&src_bits, 32) ) {
                 mips_nan = MIPS32_QNAN;
                 xc->setRegOperand(inst, 0, mips_nan);
-                if (traceData) { traceData->setData(mips_nan); }
+                if (traceData) { traceData->setData(floatRegClass, mips_nan); }
                 return true;
             }
         }
@@ -139,7 +139,7 @@ output exec {{
             //Write FCSR from FloatRegFile
             cpu->tcBase()->setReg(float_reg::Fcsr, new_fcsr);
 
-            if (traceData) { traceData->setData(mips_nan); }
+            if (traceData) { traceData->setData(floatRegClass, mips_nan); }
             return true;
         }