SMACK: Delete list_head repeated initialization

smk_copy_rules() and smk_copy_relabel() are initializing list_head though
they have been initialized already in new_task_smack() function. Delete
repeated initialization.

Signed-off-by: Himanshu Shukla <himanshu.sh@samsung.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>