target-arm/machine.c: Allow user to request GICv3 emulation

Now we have an emulated GICv3, remove the restriction in
gicv3_class_name() so that the user can request a GICv3 with
-machine gic-version=3 even when not using KVM.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Shannon Zhao <shannon.zhao@linaro.org>
Tested-by: Shannon Zhao <shannon.zhao@linaro.org>
Message-id: 1465915112-29272-20-git-send-email-peter.maydell@linaro.org

target-arm/machine.c

@@ -342,8 +342,7 @@ const char *gicv3_class_name(void)
                      "platform");
 #endif
     } else {
-        /* TODO: Software emulation is not implemented yet */
-        error_report("KVM is currently required for GICv3 emulation");
+        return "arm-gicv3";
     }
 
     exit(1);