[nrf noup] boards: arm: thingy53: Disable USB CDC added by MCUBoot

Enabling USB CDC by default in Thingy:53 board configuration
caused that there were two instances of USB CDC in MCUBoot. Change
disables one instance which was added automatically by NCS if
MCUBoot bootloader was built as a child image.

Jira: NCSDK-18596

Signed-off-by: Mateusz Kapala <[email protected]>
Signed-off-by: Johann Fischer <[email protected]>
(cherry picked from commit 6d1e377)

Author: mkapala-nordic

boards/nordic/thingy53/Kconfig.defconfig

@@ -84,6 +84,13 @@ endif # !TRUSTED_EXECUTION_SECURE
 
 source "boards/common/usb/Kconfig.cdc_acm_serial.defconfig"
 
+# By default, a USB CDC ACM instance is already enabled in the board's DTS.
+# It is not necessary for nRF Connect SDK to add another instance if MCUBoot
+# bootloader is built as a child image.
+config MCUBOOT_USB_SUPPORT
+	bool
+	default n
+
 endif # BOARD_THINGY53_NRF5340_CPUAPP || BOARD_THINGY53_NRF5340_CPUAPP_NS
 
 if BOARD_THINGY53_NRF5340_CPUNET