dev: Fix -Wunused-variable in structured binding

Change-Id: Ia244767dd9d1dd7b72c320fb78e48f206694f5a2
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/66891
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Yu-hsin Wang <yuhsingw@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>

src/dev/reg_bank.hh

@@ -1018,8 +1018,8 @@ class RegisterBank : public RegisterBankBase
     virtual void
     reset()
     {
-        for (auto &[offset, reg]: _offsetMap)
-            reg.get().reset();
+        for (auto &it: _offsetMap)
+            it.second.get().reset();
     }
 };