cpu-minor: Use the RegClassInfo::regName method instead of THE_ISA.

Jira Issue: https://gem5.atlassian.net/browse/GEM5-1060

Change-Id: I43b31897ed3a9e77c6d2908ac4a04f705a0f74f2
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/48708
Reviewed-by: Hoa Nguyen <hoanguyen@ucdavis.edu>
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/cpu/minor/dyn_inst.cc

@@ -147,14 +147,7 @@ printRegName(std::ostream &os, const RegId& reg,
       case MiscRegClass:
         {
             RegIndex misc_reg = reg.index();
-
-        /* This is an ugly test because not all archs. have miscRegName */
-#if THE_ISA == ARM_ISA
-            os << 'm' << misc_reg << '(' << TheISA::miscRegName[misc_reg] <<
-                ')';
-#else
-            os << 'n' << misc_reg;
-#endif
+            os << 'm' << misc_reg << '(' << reg_class.regName(reg) << ')';
         }
         break;
       case FloatRegClass: