ARM: dts: at91: sama5d2_xplained: Fix the flx4 i2c label numbering

A better version of this has already been sent to mainline, do not
port this from a release to another.

The sama5d2 SoC has the following IPs: [uart0, uart4], {spi0, spi1},
{i2c0, i2c1}. The flexcom functions should be labeled in order:
flx0: uart5, spi2, i2c2
flx1: uart6, spi3, i2c3
flx2: uart7, spi4, i2c4
flx3: uart8, spi5, i2c5
flx4: uart9, spi6, i2c6

Fix the label number for flx4 i2c.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>

Author: ambarus

arch/arm/boot/dts/at91-sama5d2_xplained.dts

@@ -378,7 +378,7 @@
 				atmel,flexcom-mode = <ATMEL_FLEXCOM_MODE_TWI>;
 				status = "okay";
 
-				i2c2: i2c@600 {
+				i2c6: i2c@600 {
 					compatible = "atmel,sama5d2-i2c";
 					reg = <0x600 0x200>;
 					interrupts = <23 IRQ_TYPE_LEVEL_HIGH 7>;