samples: cdc_acm: add config overlay for cdc_acm+dfu

Add config overlay for cdc_acm+dfu composite configuration.
Manual configuration over menuconfig may be error-prone for
the user because then FLASH_LOAD_OFFSET and FLASH_LOAD_SIZE
should also to be set to appropriate values.

Signed-off-by: Johann Fischer <[email protected]>

Author: jfischer-no

samples/subsys/usb/cdc_acm/overlay-composite-cdc-dfu.conf

@@ -0,0 +1,10 @@
+# Overlay file for composite configuration
+# CDC ACM + USB DFU
+
+CONFIG_USB_COMPOSITE_DEVICE=y
+
+CONFIG_USB_DFU_CLASS=y
+CONFIG_FLASH=y
+CONFIG_IMG_MANAGER=y
+CONFIG_FLASH_PAGE_LAYOUT=y
+CONFIG_BOOTLOADER_MCUBOOT=y