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.

Platforms/PlatformEsp32/Bindings/espressif,esp32-i2s.yaml

@@ -0,0 +1,33 @@
+description: ESP32 I2S Controller
+
+include: ["i2s-controller.yaml"]
+
+compatible: "espressif,esp32-i2s"
+
+properties:
+  port:
+    type: int
+    required: true
+    description: |
+      The port number, defined by i2s_port_t.
+      Depending on the hardware, these values are available: I2S_NUM_0, I2S_NUM_1
+  pin-bclk:
+    type: int
+    required: true
+    description: BCK pin
+  pin-ws:
+    type: int
+    required: true
+    description: WS pin
+  pin-data-out:
+    type: int
+    required: true
+    description: DATA OUT pin
+  pin-data-in:
+    type: int
+    required: true
+    description: DATA IN pin
+  pin-mclk:
+    type: int
+    required: true
+    description: MCLK pin