I2S driver implementation (#480)

* **New Features**
  * ESP32 I2S controller support: runtime-configurable digital audio I/O with read/write/set/get operations and multiple formats.

* **Board Support**
  * LilyGO T-Deck device tree entry added to enable I2S peripheral pin configuration.

* **Documentation**
  * New/updated bindings and descriptors for I2S, I2C, GPIO, and root nodes.

* **Other**
  * Added GPIO "no pin" sentinel and exposed I2S controller API symbols.

TactilityKernel/Bindings/gpio-controller.yaml

@@ -1,3 +1,4 @@
+description: GPIO controller
 properties:
   gpio-count:
     type: int

TactilityKernel/Bindings/i2c-controller.yaml

@@ -1 +1 @@
-bus: i2c
+description: I2C controller

TactilityKernel/Bindings/i2c-device.yaml

@@ -1,4 +1,4 @@
-on-bus: i2c
+description: I2C device
 
 properties:
   register:

TactilityKernel/Bindings/i2s-controller.yaml

@@ -0,0 +1 @@
+description: I2S controller

TactilityKernel/Bindings/root.yaml

@@ -1,3 +1,5 @@
+description: Represents root node of a device tree. It holds all other nodes.
+
 compatible: "root"
 
 properties: