iwl3945: fix some warnings when compiled without debug

Fix the following warnings if compiled without CONFIG_IWLWIFI_DEBUG.

drivers/net/wireless/iwlwifi/iwl3945-base.c: In function ‘iwl3945_rx_reply_add_sta’:
drivers/net/wireless/iwlwifi/iwl3945-base.c:2748: warning: unused variable ‘pkt’
drivers/net/wireless/iwlwifi/iwl3945-base.c: In function ‘iwl3945_rx_scan_results_notif’:
drivers/net/wireless/iwlwifi/iwl3945-base.c:2903: warning: unused variable ‘notif’
drivers/net/wireless/iwlwifi/iwl3945-base.c: In function ‘iwl3945_rx_scan_complete_notif’:
drivers/net/wireless/iwlwifi/iwl3945-base.c:2928: warning: unused variable ‘scan_notif’

Signed-off-by: Helmut Schaa <helmut.schaa@googlemail.com>
Acked-by: Samuel Ortiz <samuel.ortiz@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>