of: overlay: Fix of_overlay_fdt_apply prototype when !CONFIG_OF_OVERLAY

The of_overlay_fdt_apply has been changed but when CONFIG_OF_OVERLAY
support is not configured then old stub prototype is declared
by of.h header.

Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>
Fixes: 47284862 ("of: overlay: Extend of_overlay_fdt_apply() to specify the target node")
Acked-by: Marc Kleine-Budde <mkl@pengutronix.de>
Link: https://lore.kernel.org/r/20230904100002.7913-1-pisa@cmp.felk.cvut.cz


Signed-off-by: Rob Herring <robh@kernel.org>