+generate_deps_for_ns() {
+    $SPATCH --very-quiet --in-place --sp-file \
+	    $srctree/scripts/coccinelle/misc/add_namespace.cocci -D ns=$1 $2
+}

* Where will the variable “srctree” be set for the file “scripts/nsdeps”?

* Would you like to support a separate build directory for desired adjustments?

* How do you think about to check error handling around such commands?

+generate_deps() {

…

+        for source_file in $mod_source_files; do
+            sed '/MODULE_IMPORT_NS/Q' $source_file > ${source_file}.tmp

…

I suggest to assign the name for the temporary file to a variable
which should be used by subsequent commands.

Regards,
Markus