cocci: merge mfree.cocci and mfree_return.cocci (#30838)

It makes sense that these should be one file instead of two, as they both involve mfree()

coccinelle/mfree.cocci

@@ -1,7 +1,36 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
+@@
+/* Avoid running this transformation on the mfree function itself */
+position p : script:python() { p[0].current_element != "mfree" };
+expression e;
+@@
+- free@p(e);
+- return NULL;
++ return mfree(e);
+
 @@
 expression p;
 @@
 - free(p);
 - p = NULL;
 + p = mfree(p);
+
+@@
+expression p;
+@@
+- if (p)
+-          free(p);
++ free(p);
+
+@@
+expression p;
+@@
+- if (p)
+-          mfree(p);
++ free(p);
+
+@@
+expression p;
+@@
+- mfree(p);
++ free(p);

coccinelle/mfree_return.cocci

@@ -1,9 +0,0 @@
-/* SPDX-License-Identifier: LGPL-2.1-or-later */
-@@
-/* Avoid running this transformation on the mfree function itself */
-position p : script:python() { p[0].current_element != "mfree" };
-expression e;
-@@
-- free@p(e);
-- return NULL;
-+ return mfree(e);