Add chardev config option

The libgpiod module requires a chardev added with linux kernel 4.8.
The default chardev is /dev/gpiochip0. Subsequent devices follow this
schema: /dev/gpiochipN.

pi_mqtt_gpio/__init__.py

@@ -127,6 +127,10 @@ gpio_modules:
         type: boolean
         required: no
         default: yes
+      chip:
+        type: string
+        required: no
+        default: "/dev/gpiochip0"
 
 sensor_modules:
   type: list

pi_mqtt_gpio/modules/__init__.py

@@ -8,6 +8,7 @@ BASE_SCHEMA = {
     "name": {"required": True, "empty": False},
     "module": {"required": True, "empty": False},
     "cleanup": {"required": False, "type": "boolean", "default": True},
+    "chip": {"required": False, "type": "string", "default": "/dev/gpiochip0"},
 }
 
 

pi_mqtt_gpio/modules/gpiod.py

@@ -22,7 +22,7 @@ class GPIO(GenericGPIO):
         import gpiod as gpio
 
         self.io = gpio
-        self.chip = config.chip
+        self.chip = gpio.chip(config["chip"])
         self.pins = {}
         self.watchers = {}