cmake: DTS post-processing of ELF file depends on CONFIG_HAS_DTS
cmake: DTS post-processing of ELF file depends on CONFIG_HAS_DTS

Only run gen_handles.py if CONFIG_HAS_DTS is set. This enables vendors
without device tree implementations to compile without the generated
dependencies.

Signed-off-by: Morten Priess <eeac701aa7fa64292a00ac226283761853032460@oticon.com>

zephyrproject-rtos/zephyr,finikorg/zephyr,finikorg/zephyr,finikorg/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,galak/zephyr,galak/zephyr