iwl3945: read rev id in nic config

Read rev id in nic_config instead of nic_init.
Nic_config has some checking for rev_id but we actually don't read
the rev_id in there.

Signed-off-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>