arch-arm: De-virtualize updateIntState

De-virtualize updateIntState and replace it with the new blockIntUpdate
in the MuxingKvmGic class.

The monolithic updateIntState is GicV2 specific and it is not compatible
with the more complex IRQ update logic in GicV3, which is delegating the
update to the destributor/redistributor/cpuinterface classes

Rather than stubbing the update function the MuxingKvmGic class, we
override the blockIntUpdate to return true in case a KVM gic is in use.
This is loosening the interface, not restricting any GIC implementation
to a specific update interface/design

Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Change-Id: Ib8d9c99b720c779a2255ac47ee2a655ff281581d
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/55609
Reviewed-by: Richard Cooper <richard.cooper@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/dev/arm/gic_v2.hh

@@ -448,7 +448,7 @@ class GicV2 : public BaseGic, public BaseGicRegisters
     /** See if some processor interrupt flags need to be enabled/disabled
      * @param hint which set of interrupts needs to be checked
      */
-    virtual void updateIntState(int hint);
+    void updateIntState(int hint);
 
     /** Update the register that records priority of the highest priority
      *  active interrupt*/