arch-arm: Remove setters from SoftwareStep

Motivation:
Those helpers are used and meant to be used by the parent
(SelfDebug) class only. There is no point on exposing them to
the outer world. Better to make SelfDebug a friend class and to
allow it to access children's private data.

Change-Id: Ib945b1aa46742b90062ce7a5de563f164127075f
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/32774
Reviewed-by: Richard Cooper <richard.cooper@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/arch/arm/self_debug.hh

@@ -204,6 +204,8 @@ class SoftwareStep
     bool cpsrD;
 
   public:
+    friend class SelfDebug;
+
     SoftwareStep(SelfDebug *s)
       : bSS(false), stateSS(INACTIVE_STATE),
         conf(s), steppedLdx(false)
@@ -213,18 +215,6 @@ class SoftwareStep
                                 ExceptionLevel dest);
     bool advanceSS(ThreadContext *tc);
 
-    inline void
-    setCPSRD(bool val)
-    {
-        cpsrD = val;
-    }
-
-    inline void
-    setEnableSS(bool val)
-    {
-        bSS = val;
-    }
-
     void
     setLdx()
     {
@@ -391,7 +381,7 @@ class SelfDebug
     {
         enableFlag = bits(val, 15);
         bKDE = bits(val, 13);
-        softStep->setEnableSS((bool)bits(val, 0));
+        softStep->bSS = bits(val, 0);
     }
 
     inline void
@@ -427,7 +417,7 @@ class SelfDebug
     inline void
     setDebugMask(bool mask)
     {
-        softStep->setCPSRD(mask);
+        softStep->cpsrD = mask;
     }
 
     inline bool