Fix memory leak of f2fs_info

'struct f2fs_info' from system/extras/f2fs_utils is supposed to be
freed using free_f2fs_info(), not just free().

Test: see I08fc8465f7962abd698904b5466f3ed080d53953
Change-Id: If6e75e5c604b40be24538b156a37cc76f4f0d4f7
diff --git a/EncryptInplace.cpp b/EncryptInplace.cpp
index 4c1bb73..eb7d4c3 100644
--- a/EncryptInplace.cpp
+++ b/EncryptInplace.cpp
@@ -423,7 +423,7 @@
     if (rc) LOG(ERROR) << "Failed to encrypt f2fs filesystem on " << real_blkdev;
 
     log_progress_f2fs(0, true);
-    free(f2fs_info);
+    free_f2fs_info(f2fs_info);
     free(data.buffer);
     close(data.realfd);
     close(data.cryptofd);