Bluetooth: Add macros for filter duplicates values

This patch adds macros for filter_duplicates parameter values from
HCI LE Set Scan Enable command. It also fixes le_scan_enable_req
function so it uses the LE_SCAN_FILTER_DUP_ENABLE macro instead of
a magic number.

The LE_SCAN_FILTER_DUP_DISABLE was also defined since it will be
required to properly support the GAP Observer Role.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Acked-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>

include/net/bluetooth/hci.h

@@ -998,6 +998,8 @@ struct hci_cp_le_set_scan_param {
 
 #define LE_SCANNING_DISABLED		0x00
 #define LE_SCANNING_ENABLED		0x01
+#define LE_SCAN_FILTER_DUP_DISABLE	0x00
+#define LE_SCAN_FILTER_DUP_ENABLE	0x01
 
 #define HCI_OP_LE_SET_SCAN_ENABLE	0x200c
 struct hci_cp_le_set_scan_enable {

net/bluetooth/hci_core.c

@@ -1990,7 +1990,7 @@ static void le_scan_enable_req(struct hci_request *req, unsigned long opt)
 
 	memset(&cp, 0, sizeof(cp));
 	cp.enable = 1;
-	cp.filter_dup = 1;
+	cp.filter_dup = LE_SCAN_FILTER_DUP_ENABLE;
 
 	hci_req_add(req, HCI_OP_LE_SET_SCAN_ENABLE, sizeof(cp), &cp);
 }