arm: stellaris: exit on external reset request Add GPIO in for the stellaris board which calls qemu_system_reset_request() on reset request. Signed-off-by: Michael Davidsaver <mdavidsaver@gmail.com> Reviewed-by: Peter Crosthwaite <crosthwaite.peter@gmail.com> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>