zd1211rw: Implement get_tsf()

This patch implements get_tsf() of ieee80211_ops in the zd1211rw driver.

Signed-off-by: Alina Friedrichsen <x-alina@gmx.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/zd1211rw/zd_mac.c b/drivers/net/wireless/zd1211rw/zd_mac.c
index da9214e..0b01ff0 100644
--- a/drivers/net/wireless/zd1211rw/zd_mac.c
+++ b/drivers/net/wireless/zd1211rw/zd_mac.c
@@ -935,6 +935,12 @@
 	}
 }
 
+static u64 zd_op_get_tsf(struct ieee80211_hw *hw)
+{
+	struct zd_mac *mac = zd_hw_mac(hw);
+	return zd_chip_get_tsf(&mac->chip);
+}
+
 static const struct ieee80211_ops zd_ops = {
 	.tx			= zd_op_tx,
 	.start			= zd_op_start,
@@ -945,6 +951,7 @@
 	.config_interface	= zd_op_config_interface,
 	.configure_filter	= zd_op_configure_filter,
 	.bss_info_changed	= zd_op_bss_info_changed,
+	.get_tsf		= zd_op_get_tsf,
 };
 
 struct ieee80211_hw *zd_mac_alloc_hw(struct usb_interface *intf)