can: ifi: Add DT bindings for ifi,canfd

Add device tree bindings for the I/F/I CANFD controller IP core.
Signed-off-by: NMarek Vasut <marex@denx.de>
Cc: Marc Kleine-Budde <mkl@pengutronix.de>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Oliver Hartkopp <socketcan@hartkopp.net>
Cc: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>

Documentation/devicetree/bindings/net/can/ifi_canfd.txt

+IFI CANFD controller
+--------------------
+
+Required properties:
+  - compatible: Should be "ifi,canfd-1.0"
+  - reg: Should contain CAN controller registers location and length
+  - interrupts: Should contain IRQ line for the CAN controller
+
+Example:
+
+	canfd0: canfd@ff220000 {
+		compatible = "ifi,canfd-1.0";
+		reg = <0xff220000 0x00001000>;
+		interrupts = <0 43 0>;
+	};