arm: Get rid of pointless have_generic_timer param

The ArmSystem class has a parameter to indicate whether it is
configured to use the generic timer extension or not. This parameter
doesn't affect any feature flags in the current implementation and is
therefore completely unnecessary. In fact, we usually don't set it
even if a system has a generic timer. If we ever need to check if
there is a generic timer present, we should just request a pointer and
check if it is non-null instead.

src/arch/arm/ArmSystem.py

@@ -58,8 +58,6 @@ class ArmSystem(System):
     have_virtualization = Param.Bool(False,
         "True if Virtualization Extensions are implemented")
     have_lpae = Param.Bool(False, "True if LPAE is implemented")
-    have_generic_timer = Param.Bool(False,
-        "True if the Generic Timer extension is implemented")
     highest_el_is_64 = Param.Bool(False,
         "True if the register width of the highest implemented exception level "
         "is 64 bits (ARMv8)")

src/arch/arm/system.cc

@@ -57,7 +57,6 @@ ArmSystem::ArmSystem(Params *p)
     : System(p), bootldr(NULL), _haveSecurity(p->have_security),
       _haveLPAE(p->have_lpae),
       _haveVirtualization(p->have_virtualization),
-      _haveGenericTimer(p->have_generic_timer),
       _genericTimer(nullptr),
       _highestELIs64(p->highest_el_is_64),
       _resetAddr64(p->reset_addr_64),

src/arch/arm/system.hh

@@ -84,11 +84,6 @@ class ArmSystem : public System
      */
     const bool _haveVirtualization;
 
-    /**
-     * True if this system implements the Generic Timer extension
-     */
-    const bool _haveGenericTimer;
-
     /**
      * Pointer to the Generic Timer wrapper.
      */
@@ -157,9 +152,6 @@ class ArmSystem : public System
       */
     bool haveVirtualization() const { return _haveVirtualization; }
 
-    /** Returns true if this system implements the Generic Timer extension. */
-    bool haveGenericTimer() const { return _haveGenericTimer; }
-
     /** Sets the pointer to the Generic Timer. */
     void setGenericTimer(GenericTimer *generic_timer)
     {