iwlwifi: dont use pci_dev before it being assign

In order to use build-in debugging macro, pci_dev in priv need to be
assigned first.

This fix iwl3945 driver oopsed at boot with 2.6.37-rc1

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