hal/drivers/hal_vti.c:  silence -Wunused-but-set-variable warnings
hal/drivers/hal_vti.c:  silence -Wunused-but-set-variable warnings

Silence warning by incrementing `junk` varible.

    hal/drivers/hal_vti.c: In function ‘vti_dac_write’:
    hal/drivers/hal_vti.c:794:11: warning: variable ‘junk’ set but not
      used [-Wunused-but-set-variable]
	 short junk;
	       ^

strahlex/machinekit,strahlex/machinekit,strahlex/machinekit,strahlex/machinekit,strahlex/machinekit,strahlex/machinekit,strahlex/machinekit