iwlwifi: update reply_statistics_cmd with 'clear' parameter

When issue REPLY_STATISTICS_CMD to uCode, two possible flag
can be set in the configuration flags

bit 0: Clear statistics
       0: Do not clear Statistics counters
       1: Clear to zero Statistics counters

Allow "clear" parameter to be set from the caller.

Add debugfs file to clear the statistics counters to help monitor and
debug the uCode behavior.

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@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-commands.h b/drivers/net/wireless/iwlwifi/iwl-commands.h
index 2857287..6e23a2b 100644
--- a/drivers/net/wireless/iwlwifi/iwl-commands.h
+++ b/drivers/net/wireless/iwlwifi/iwl-commands.h
@@ -3071,6 +3071,10 @@
 	__le32 reserved3;
 } __attribute__ ((packed));
 
+#define UCODE_STATISTICS_CLEAR_MSK		(0x1 << 0)
+#define UCODE_STATISTICS_FREQUENCY_MSK		(0x1 << 1)
+#define UCODE_STATISTICS_NARROW_BAND_MSK	(0x1 << 2)
+
 /*
  * REPLY_STATISTICS_CMD = 0x9c,
  * 3945 and 4965 identical.