[nrf toup] cmake: Align with renaming kernel_elf to zephyr_final

Upstream changed the name of 'kernel_elf' to 'zephyr_final', in this
commit we do the same renaming.

Signed-off-by: Sebastian Bøe <[email protected]>

Author: SebastianBoe

zephyr/CMakeLists.txt

@@ -27,7 +27,7 @@ if(CONFIG_BOOTLOADER_MCUBOOT)
     set(to_sign_hex
       $<IF:${sign_merged},${merged_hex_file},${PROJECT_BINARY_DIR}/${KERNEL_HEX_NAME}>)
     set(sign_depends
-      $<IF:${sign_merged},${merged_hex_file_depends},kernel_elf>)
+      $<IF:${sign_merged},${merged_hex_file_depends},zephyr_final>)
     set(sign_cmd
       ${PYTHON_EXECUTABLE}
       ${MCUBOOT_BASE}/scripts/imgtool.py