iwlwifi: use station HT capabilities and BSS operating mode for Green-field

Green-field mode should be configured in the HT station table.  This patch uses
both the per-station GF support flag as well as the current BSS HT operation
mode (non-GF stations present flag).

Added the "ht_greenfield_support" field to struct iwl_cfg to replace the
device-specific check in rs_use_green().  That check has been moved to
iwlcore_init_ht_hw_capab().

Signed-off-by: Daniel C Halperin <daniel.c.halperin@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-core.h b/drivers/net/wireless/iwlwifi/iwl-core.h
index 5096834..4ca025a 100644
--- a/drivers/net/wireless/iwlwifi/iwl-core.h
+++ b/drivers/net/wireless/iwlwifi/iwl-core.h
@@ -251,6 +251,7 @@
 	enum iwl_pa_type pa_type;
 	const u16 max_ll_items;
 	const bool shadow_ram_support;
+	const bool ht_greenfield_support;
 };
 
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