iwl3945: prevent too frequent firmware resets

Similarly like on iwlagn, initialize reset duration on iwl3945 to prevent
too frequent firmware resets.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Acked-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>