boot: zephyr: Use mcuboot-led0 in MCUBOOT_INDICATION_LED help section

bootloader-led0 is deprecated. Replace with mcuboot-led0 in
MCUBOOT_INDICATION_LED help.

Signed-off-by: Jeppe Odgaard <jeppe.odgaard@prevas.dk>
diff --git a/boot/zephyr/Kconfig b/boot/zephyr/Kconfig
index c7e2e99..67ac4a6 100644
--- a/boot/zephyr/Kconfig
+++ b/boot/zephyr/Kconfig
@@ -501,7 +501,7 @@
 	default n
 	help
 	  Device device activates the LED while in bootloader mode.
-	  bootloader-led0 alias must be set in the device's .dts
+	  mcuboot-led0 alias must be set in the device's .dts
 	  definitions for this to work.
 
 rsource "Kconfig.serial_recovery"