arm64: dts: vexpress: Fix VExpress LED names

The common LED binding wants the LED node names to start with led- and
then have just a single number.

Changing the naming for the 8 user LEDs from using user<x> to led-<x>.
Also there is no default-trigger named "mmc0" in the kernel, so use the
more generic "disk-activity".

Link: https://lore.kernel.org/r/20200513103016.130417-18-andre.przywara@arm.com
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

arch/arm/boot/dts/vexpress-v2m-rs1.dtsi

@@ -51,49 +51,49 @@
 	leds {
 		compatible = "gpio-leds";
 
-		user1 {
+		led-1 {
 			label = "v2m:green:user1";
 			gpios = <&v2m_led_gpios 0 0>;
 			linux,default-trigger = "heartbeat";
 		};
 
-		user2 {
+		led-2 {
 			label = "v2m:green:user2";
 			gpios = <&v2m_led_gpios 1 0>;
 			linux,default-trigger = "disk-activity";
 		};
 
-		user3 {
+		led-3 {
 			label = "v2m:green:user3";
 			gpios = <&v2m_led_gpios 2 0>;
 			linux,default-trigger = "cpu0";
 		};
 
-		user4 {
+		led-4 {
 			label = "v2m:green:user4";
 			gpios = <&v2m_led_gpios 3 0>;
 			linux,default-trigger = "cpu1";
 		};
 
-		user5 {
+		led-5 {
 			label = "v2m:green:user5";
 			gpios = <&v2m_led_gpios 4 0>;
 			linux,default-trigger = "cpu2";
 		};
 
-		user6 {
+		led-6 {
 			label = "v2m:green:user6";
 			gpios = <&v2m_led_gpios 5 0>;
 			linux,default-trigger = "cpu3";
 		};
 
-		user7 {
+		led-7 {
 			label = "v2m:green:user7";
 			gpios = <&v2m_led_gpios 6 0>;
 			linux,default-trigger = "cpu4";
 		};
 
-		user8 {
+		led-8 {
 			label = "v2m:green:user8";
 			gpios = <&v2m_led_gpios 7 0>;
 			linux,default-trigger = "cpu5";