zephyr: lib: regions_mm: add missing init.h

Because module uses SYS_INIT defined in init.h. Things likely worked
because of indirect includes.

Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>

Author: gmarull

zephyr/lib/regions_mm.c

@@ -5,6 +5,8 @@
  * Author: Jakub Dabek <jakub.dabek@intel.com>
  */
 
+#include <zephyr/init.h>
+
 #include <sof/lib/regions_mm.h>
 
 /* list of vmh_heap objects created */