iwl3945: Remaining host command cleanups

With the recent host command routines merge, we can now look at the various
host command helpers and get rid of the duplicated ones.

Signed-off-by: Samuel Ortiz <samuel.ortiz@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>