dt-bindings: use dt-bindings/dt-util.h instead of sys/util_macro.h

Replaces some usages of <zephyr/sys/util_macro.h> with
<zephyr/dt-bindings/dt-util.h> such that this is done in a uniform way.

The latter being a wrapper around the former, which was introduced in
PR #28779 with the intention to be able to retain the pattern of only
including <zephyr/dt-bindings/foo.h> files in in-tree dts files.

Signed-off-by: Thomas Stranger <thomas.stranger@outlook.com>