iwl3945: replaces iwl3945_priv with iwl_priv

The patch replaces iwl3945_priv to iwl_priv. It adds 3945 specific
data members to iwl_priv.

Signed-off-by: Abhijeet Kolekar <abhijeet.kolekar@intel.com>
Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>