sandbox: Fix quiting when the LCD window is closed

With recent changes to how sandbox handles reset, closing the window
currently just restarts sandbox.

Use the correct sysreset type to tell it to shut down.

Signed-off-by: Simon Glass <sjg@chromium.org>

arch/sandbox/cpu/sdl.c

@@ -6,6 +6,7 @@
 #include <errno.h>
 #include <unistd.h>
 #include <stdbool.h>
+#include <sysreset.h>
 #include <linux/input.h>
 #include <SDL2/SDL.h>
 #include <asm/state.h>
@@ -81,7 +82,7 @@ static void sandbox_sdl_poll_events(void)
 		switch (event.type) {
 		case SDL_QUIT:
 			puts("LCD window closed - quitting\n");
-			reset_cpu();
+			sysreset_walk(SYSRESET_POWER_OFF);
 			break;
 		}
 	}