Remove const from dtc_file::dir.

Signed-off-by: Scott Wood <scottwood@freescale.com>
diff --git a/srcpos.c b/srcpos.c
index 7d0f0a7..c8eaa1e 100644
--- a/srcpos.c
+++ b/srcpos.c
@@ -104,7 +104,7 @@
 	}
 
 out:
-	free((void *)file->dir);
+	free(file->dir);
 	free(file);
 	return NULL;
 }
@@ -114,6 +114,6 @@
 	if (fclose(file->file))
 		die("Error closing \"%s\": %s\n", file->name, strerror(errno));
 
-	free((void *)file->dir);
+	free(file->dir);
 	free(file);
 }