feat(drivers): Support init high/low in 595 driver

Add support for initializing a pin to a given high/low value during
configuration. Needed for proper initialization by systems like
GPIO hogs or gpio-leds Zephyr drivers.

app/module/drivers/gpio/gpio_595.c

@@ -89,6 +89,14 @@ static int setup_pin_dir(const struct device *dev, uint32_t pin, int flags) {
     return 0;
 }
 
+static int reg_595_port_set_bits_raw(const struct device *dev, uint32_t mask) {
+    return reg_595_port_set_masked_raw(dev, mask, mask);
+}
+
+static int reg_595_port_clear_bits_raw(const struct device *dev, uint32_t mask) {
+    return reg_595_port_set_masked_raw(dev, mask, 0);
+}
+
 static int reg_595_pin_config(const struct device *dev, gpio_pin_t pin, gpio_flags_t flags) {
     int ret;
 
@@ -106,6 +114,12 @@ static int reg_595_pin_config(const struct device *dev, gpio_pin_t pin, gpio_fla
         LOG_ERR("595: error setting pin direction (%d)", ret);
     }
 
+    if ((flags & GPIO_OUTPUT_INIT_LOW) != 0) {
+        return reg_595_port_clear_bits_raw(dev, BIT(pin));
+    } else if ((flags & GPIO_OUTPUT_INIT_HIGH) != 0) {
+        return reg_595_port_set_bits_raw(dev, BIT(pin));
+    }
+
     return ret;
 }
 
@@ -132,14 +146,6 @@ static int reg_595_port_set_masked_raw(const struct device *dev, uint32_t mask,
     return ret;
 }
 
-static int reg_595_port_set_bits_raw(const struct device *dev, uint32_t mask) {
-    return reg_595_port_set_masked_raw(dev, mask, mask);
-}
-
-static int reg_595_port_clear_bits_raw(const struct device *dev, uint32_t mask) {
-    return reg_595_port_set_masked_raw(dev, mask, 0);
-}
-
 static int reg_595_port_toggle_bits(const struct device *dev, uint32_t mask) {
     struct reg_595_drv_data *const drv_data = (struct reg_595_drv_data *const)dev->data;
     uint32_t buf;