iwlwifi: clean up ht config naming

Daniel Halperin pointed out that the naming
here is rather inconsistent with at least 3
different names being used for one thing in
different contexts. Rename the struct to
iwl_ht_config (rather than iwl_ht_info) and
use ht_conf as a variable for it.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Daniel C Halperin <daniel.c.halperin@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>