cpu: Stop using NumVecElemPerVecReg.

Use the register classes regName method, or if necessary, the ratio
between the size of the vector register file and the vector element
register file.

Change-Id: Ibf63ce2b3cc3e3cc3261e5a9b8dcbfdc0af5035b
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/49164
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>

src/cpu/minor/dyn_inst.cc

@@ -152,8 +152,7 @@ printRegName(std::ostream &os, const RegId& reg,
         os << 'v' << reg.index();
         break;
       case VecElemClass:
-        os << 'v' << (reg.index() / TheISA::NumVecElemPerVecReg) << '[' <<
-            (reg.index() % TheISA::NumVecElemPerVecReg) << ']';
+        os << reg_class.regName(reg);
         break;
       case IntRegClass:
         if (reg.index() == reg_class.zeroReg()) {