security: smack: fix memleak in smk_write_rules_list()

The smack_parsed_rule structure is allocated.  If a rule is successfully
installed then the last reference to the object is lost.  This patch fixes this
leak. Moreover smack_parsed_rule is allocated on stack because it no longer
needed ofter smk_write_rules_list() is finished.

Signed-off-by: Tomasz Stanislawski <t.stanislaws@samsung.com>