iwlwifi: support different num of tx and rx antennas

This patch adds infrastructure for supporting different
number of tx and rx antennas

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
3 files changed