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-rxon.c b/drivers/net/wireless/iwlwifi/iwl-agn-rxon.c
index ea4895a..00e6fc59 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn-rxon.c
+++ b/drivers/net/wireless/iwlwifi/iwl-agn-rxon.c
@@ -311,7 +311,7 @@
 	int slot0 = 300, slot1 = 0;
 	int ret;
 
-	if (priv->valid_contexts == BIT(IWL_RXON_CTX_BSS))
+	if (priv->shrd->valid_contexts == BIT(IWL_RXON_CTX_BSS))
 		return 0;
 
 	BUILD_BUG_ON(NUM_IWL_RXON_CTX != 2);