iwlagn: iwl-trans.c can't dereference iwl_priv any more

This reaches encapsulation for this file. In order to reach this:
 * move priv->valid_context to iwl_shared
 * move the last_rejected initialization to the upper layer
 * define a wrapper iwl_nic_config in the upper layer that calls to
   cfg->lib->ops->nic_config

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-agn-lib.c b/drivers/net/wireless/iwlwifi/iwl-agn-lib.c
index 7c036b9..1301887 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn-lib.c
+++ b/drivers/net/wireless/iwlwifi/iwl-agn-lib.c
@@ -659,7 +659,7 @@
 				 IWL_SCD_BE_MSK | IWL_SCD_BK_MSK |
 				 IWL_SCD_MGMT_MSK;
 	if ((flush_control & BIT(IWL_RXON_CTX_PAN)) &&
-	    (priv->valid_contexts != BIT(IWL_RXON_CTX_BSS)))
+	    (priv->shrd->valid_contexts != BIT(IWL_RXON_CTX_BSS)))
 		flush_cmd.fifo_control |= IWL_PAN_SCD_VO_MSK |
 				IWL_PAN_SCD_VI_MSK | IWL_PAN_SCD_BE_MSK |
 				IWL_PAN_SCD_BK_MSK | IWL_PAN_SCD_MGMT_MSK |