drivers: i2c: Add DTS support for i2c_sam_twihs driver

Signed-off-by: Piotr Mienkowski <piotr.mienkowski@gmail.com>

dts/bindings/i2c/atmel,sam-i2c-twihs.yaml

@@ -0,0 +1,41 @@
+#
+# Copyright (c) 2017 Piotr Mienkowski
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+---
+title: Atmel SAM Family I2C (TWIHS) node
+id: atmel,sam-i2c-twihs
+version: 0.1
+
+description: >
+    This is a representation of the Atmel SAM Family I2C (TWIHS) node
+
+inherits:
+  - !include i2c.yaml
+
+properties:
+  - compatible:
+      type: string
+      category: required
+      description: compatible strings
+      constraint: "atmel,sam-i2c-twihs"
+
+  - reg:
+      type: array
+      description: mmio register space
+      generation: define
+      category: required
+
+  - interrupts:
+      type: array
+      category: required
+      description: required interrupts
+      generation: define
+
+  - peripheral-id:
+      type: int
+      description: peripheral ID
+      generation: define
+      category: required
+...