avutil/aes_crt: free AVAESCTR struct properly

Reviewed-by: Andreas Cadhalpun <andreas.cadhalpun@googlemail.com>
Signed-off-by: James Almer <jamrial@gmail.com>

libavutil/aes_ctr.c

@@ -79,7 +79,7 @@ void av_aes_ctr_free(struct AVAESCTR *a)
 {
     if (a) {
         av_freep(&a->aes);
-        av_freep(a);
+        av_free(a);
     }
 }