attenuator: set initial state of outputs to 'low'

otherwise they might be high, which means the latch is permanently
enabled.

projects/rfdsatt/attenuator.c

@@ -153,11 +153,14 @@ void attenuator_init(const struct attenuator_cfg *cfg,
 	for (k = 0; k < ARRAY_SIZE(banks); k++) {
 		if (!pins[k])
 			continue;
+		printf("GPIO Bank %u: 0x%08lx\n", k, pins[k]);
+
 		rcc_periph_clock_enable(periph[k]);
 #ifdef STM32F1
 		gpio_set_mode(banks[k], GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, pins[k]);
 #else
 		gpio_mode_setup(banks[k], GPIO_MODE_OUTPUT, 0, pins[k]);
 #endif
+		gpio_clear(banks[k], pins[k]);
 	}
 }