iwlwifi: add 1X HW WEP support

This patch adds support for HW encryption/decryption in 1X WEP.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>