iwl3945: set STATUS_READY before commit_rxon

Similar change as we already do for agn, need to avoid
"Error setting Tx power (-5)" message when loading module.

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>