kbuild: Enable DT symbols when CONFIG_OF_OVERLAY is used

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/1448027270-25488-1-git-send-email-geert+renesas@glider.be
---
Replacement for "ARM: DT: Enable symbols when CONFIG_OF_OVERLAY is
used".

v3:
  - Rebase on top of commit e7e2941300d258d5 ("kbuild: split device tree
    build rules into scripts/Makefile.dtbs") in v6.12-rc1,

v2:
  - Rebase on top of commit 8fcd8d1e63c05c48 ("kbuild: clean up code
    duplication in cmd_fdtoverlay") in v6.11-rc5,
  - Avoid duplicate "-@".
1 file changed