ARM: dts: lager: rename and reindex i2cexio

The rename from i2cexio to i2cexio0 is in preparation for adding
i2cexio1 which will use the demuxer for IIC1/I2C1.

The reindexing from i2c8 to i2c10 is to allow space for grouping of
additional GPIO buses to be added by follow-up patches to support demuxing
of other i2c buses.

Also note that fallback to GPIO is not provided by the hardware for IIC0/I2C0.
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
[wsa: rebased, fixed alias and removed typo in commit message]
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

arch/arm/boot/dts/r8a7790-lager.dts

@@ -50,7 +50,7 @@ / {
 	aliases {
 		serial0 = &scif0;
 		serial1 = &scifa1;
-		i2c8 = "i2cexio";
+		i2c10 = &i2cexio0;
 	};
 
 	chosen {
@@ -273,11 +273,13 @@ x13_clk: x13-clock {
 	 * bus with IIC3 on pins 110 (SCL) + 112 (SDA), select I2C0 at runtime, and
 	 * instantiate the slave device at runtime according to the documentation.
 	 * You can then communicate with the slave via IIC3.
+	 *
+	 * IIC0/I2C0 does not appear to support fallback to GPIO.
 	 */
-	i2cexio: i2c-8 {
+	i2cexio0: i2c-10 {
 		compatible = "i2c-demux-pinctrl";
 		i2c-parent = <&iic0>, <&i2c0>;
-		i2c-bus-name = "i2c-exio";
+		i2c-bus-name = "i2c-exio0";
 		#address-cells = <1>;
 		#size-cells = <0>;
 	};
@@ -596,12 +598,12 @@ &cpu0 {
 
 &i2c0	{
 	pinctrl-0 = <&i2c0_pins>;
-	pinctrl-names = "i2c-exio";
+	pinctrl-names = "i2c-exio0";
 };
 
 &iic0	{
 	pinctrl-0 = <&iic0_pins>;
-	pinctrl-names = "i2c-exio";
+	pinctrl-names = "i2c-exio0";
 };
 
 &iic1	{