Fixing some security-server cookie service functions to work on smack disabled.

Fixing some security-server cookie service functions to work on smack disabled.

[Issue#]        SSDWSSP-603
[Bug/Feature]   Nosmack security-server client tests fail due to incorrect
                security-server implementation for smack disabled.
[Cause]         Security-server cookie service generates incorrect label for
                nosmack and privilegeByCookieRequest does not check for smack.
[Solution]      Changing label to empty string and adding smack_check().
[Verification]  Running nosmack security-server client tests. Test
                tc05_check_privilege_by_cookie_nosmack and
                tc_security_server_get_smacklabel_cookie_nosmack should pass.

Change-Id: Ibf1ea7976d9442c56f718f8e4ca11939391cc8cd