iwlagn: move more functions from the start flow to the transport layer

Basically all the nic_init flow should be in the transport layer.
iwl_prepare_card_hw will move to the transport too in a separate patch.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>