iwl3945: Remove power related definitions from 3945 code

Most of the power (not TX power, but power management) structures and
definitions are duplicated accross iwl-power.h and iwl-3945.h. We should try
to only use the iwl header.

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