arch-arm: Make MISCREGs reset value configurable

Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Change-Id: I536065a2de5faeb8ab64391f8ca2aa83fb2cc82f
Reviewed-by: Richard Cooper <richard.cooper@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/70458
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/arch/arm/regs/misc.hh

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2010-2022 Arm Limited
+ * Copyright (c) 2010-2023 Arm Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -1231,6 +1231,12 @@ namespace ArmISA
             return *this;
         }
         chain
+        reset(uint64_t res_val) const
+        {
+            entry._reset = res_val;
+            return *this;
+        }
+        chain
         res0(uint64_t mask) const
         {
             entry._res0 = mask;