ecryptfs: fix a memory leak bug in parse_tag_1_packet()

In parse_tag_1_packet(), if tag 1 packet contains a key larger than
ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES, no cleanup is executed, leading to a
memory leak on the allocated 'auth_tok_list_item'. To fix this issue, go to
the label 'out_free' to perform the cleanup work.

Cc: stable@vger.kernel.org
Fixes: dddfa461 ("[PATCH] eCryptfs: Public key; packet management")
Signed-off-by: Wenwen Wang <wenwen@cs.uga.edu>
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>