kbuild: do not emit src version warning for non-modules

modpost is now called with .o files that are not modules.
So do not warn if there is no corresponding .mod
file listing .o files (in .tmp_versions/).

Signed-off-by: Sam Ravnborg <[e-mail]>

scripts/mod/sumversion.c

···
 		(int) strlen(basename) - 2, basename);
 
 	file = grab_file(filelist, &len);
-	if (!file) {
-		warn("could not find versions for %s\n", filelist);
+	if (!file)
+		/* not a module or .mod file missing - ignore */
 		return;
-	}
 
 	sources = strchr(file, '\n');
 	if (!sources) {