staging: skein: Removes unneeded #define

Removes unneeded #define SKEIN_PORT_CODE since skein_port.h is
nonexistent.

Signed-off-by: Eric Rost <eric.rost@mybabylon.net>
Reviewed-by: Jason Cooper <jason@lakedaemon.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>