ecryptfs: simplify list initialization in ecryptfs_parse_packet_set()

ecryptfs: simplify list initialization in ecryptfs_parse_packet_set()

In ecryptfs_parse_packet_set(),use LIST_HEAD() to declare and
initialize the 'auth_tok_list' list in one step instead of
using INIT_LIST_HEAD() separately.

No functional change.

Signed-off-by: Baolin Liu <liubaolin@kylinos.cn>
Signed-off-by: Tyler Hicks <code@tyhicks.com>