orinoco: Add WE-18 ioctls for WPA

Includes basic plumbing to get the data into firmware, and retrieve it.

SIOCxIWGENIE simply record (and return) the IE, and do not act on it.

SIOCxIWENCODEEXT, SIOCxIWAUTH and SIOCSIWMLME should be as functional as
the driver will support.

Signed-off-by: David Kilroy <kilroyd@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>