iwlagn: enable shadow register

For 6000 series devices and up, enable automatic update MAC's register
for better power usage in PSP mode

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-core.h b/drivers/net/wireless/iwlwifi/iwl-core.h
index 6064bc4..ee8cf24 100644
--- a/drivers/net/wireless/iwlwifi/iwl-core.h
+++ b/drivers/net/wireless/iwlwifi/iwl-core.h
@@ -290,6 +290,7 @@
  *	sensitivity calibration operation
  * @chain_noise_calib_by_driver: driver has the capability to perform
  *	chain noise calibration operation
+ * @shadow_reg_enable: HW shadhow register bit
 */
 struct iwl_base_params {
 	int eeprom_size;
@@ -320,6 +321,7 @@
 	const bool ucode_tracing;
 	const bool sensitivity_calib_by_driver;
 	const bool chain_noise_calib_by_driver;
+	const bool shadow_reg_enable;
 };
 /*
  * @advanced_bt_coexist: support advanced bt coexist