dt-bindings: nfc: st,st21nfca: convert to dtschema

Convert the ST ST21NFCA NFC controller to DT schema format.

Changes during bindings conversion:
1. Add a new required "interrupts" property, because it was missing in
   the old bindings by mistake.
2. Drop the "clock-frequency" property during conversion because it is a
   property of I2C bus controller, not I2C slave device.  It was also
   never used by the driver.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Link: https://lore.kernel.org/r/20211011073934.34340-5-krzysztof.kozlowski@canonical.comSigned-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/net/nfc/st,st21nfca.yaml

+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/net/nfc/st,st21nfca.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: STMicroelectronics SAS ST21NFCA NFC controller
+
+maintainers:
+  - Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
+
+properties:
+  compatible:
+    const: st,st21nfca-i2c
+
+  enable-gpios:
+    description: Output GPIO pin used for enabling/disabling the controller
+
+  ese-present:
+    type: boolean
+    description: |
+      Specifies that an ese is physically connected to the controller
+
+  interrupts:
+    maxItems: 1
+
+  reg:
+    maxItems: 1
+
+  uicc-present:
+    type: boolean
+    description: |
+      Specifies that the uicc swp signal can be physically connected to the
+      controller
+
+required:
+  - compatible
+  - enable-gpios
+  - interrupts
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        nfc@1 {
+            compatible = "st,st21nfca-i2c";
+            reg = <0x1>;
+
+            interrupt-parent = <&gpio5>;
+            interrupts = <2 IRQ_TYPE_LEVEL_LOW>;
+            enable-gpios = <&gpio5 29 GPIO_ACTIVE_HIGH>;
+
+            ese-present;
+            uicc-present;
+        };
+    };

Documentation/devicetree/bindings/net/nfc/st21nfca.txt

-* STMicroelectronics SAS. ST21NFCA NFC Controller
-
-Required properties:
-- compatible: Should be "st,st21nfca-i2c".
-- clock-frequency: I²C work frequency.
-- reg: address on the bus
-- enable-gpios: Output GPIO pin used for enabling/disabling the ST21NFCA
-
-Optional SoC Specific Properties:
-- pinctrl-names: Contains only one value - "default".
-- pintctrl-0: Specifies the pin control groups used for this controller.
-- ese-present: Specifies that an ese is physically connected to the nfc
-controller.
-- uicc-present: Specifies that the uicc swp signal can be physically
-connected to the nfc controller.
-
-Example (for ARM-based BeagleBoard xM with ST21NFCA on I2C2):
-
-&i2c2 {
-
-
-	st21nfca: st21nfca@1 {
-
-		compatible = "st,st21nfca-i2c";
-
-		reg = <0x01>;
-		clock-frequency = <400000>;
-
-		interrupt-parent = <&gpio5>;
-		interrupts = <2 IRQ_TYPE_LEVEL_LOW>;
-
-		enable-gpios = <&gpio5 29 GPIO_ACTIVE_HIGH>;
-
-		ese-present;
-		uicc-present;
-	};
-};