scripts: dts: gen_defines: add DT_DEBRACKET_INTERNAL helper

Add a utility macro used to remove brackets from around a single
argument. While __DEBRACKET exists in util_internal.h, this change makes
DT independent (otherwise we should include util_internal.h, which is
another option).

Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>
diff --git a/scripts/dts/gen_defines.py b/scripts/dts/gen_defines.py
index 6bff4cb..88fcf1c 100755
--- a/scripts/dts/gen_defines.py
+++ b/scripts/dts/gen_defines.py
@@ -102,6 +102,8 @@
     with open(args.header_out, "w", encoding="utf-8") as header_file:
         write_top_comment(edt)
 
+        write_utils()
+
         # populate all z_path_id first so any children references will
         # work correctly.
         for node in sorted(edt.nodes, key=lambda node: node.dep_ordinal):
@@ -239,6 +241,13 @@
     out_comment(s, blank_before=False)
 
 
+def write_utils():
+    # Writes utility macros
+
+    out_comment("Used to remove brackets from around a single argument")
+    out_define("DT_DEBRACKET_INTERNAL(...)", "__VA_ARGS__")
+
+
 def write_node_comment(node):
     # Writes a comment describing 'node' to the header and configuration file