iwl3945: fix sparse error

error is:
iwl3945-base.c:545:5: warning: symbol 'iwl3945_set_dynamic_key' was not
declared. Should it be static?

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>