configure the SWD frequency when setting adapter speed in SWD mode for versaloon

Change-Id: I99cdc11ba1442e4c9efaa0f1de8e7089ec725e14
Signed-off-by: Simon Qian <openocd@versaloon.com>
Reviewed-on: http://openocd.zylin.com/2608
Tested-by: jenkins
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>

src/jtag/drivers/vsllink.c

@@ -242,8 +242,10 @@ static int vsllink_execute_queue(void)
 
 static int vsllink_speed(int speed)
 {
-	if (swd_mode)
+	if (swd_mode) {
+		vsllink_swd_frequency(NULL, speed * 1000);
 		return ERROR_OK;
+	}
 
 	versaloon_interface.adaptors.jtag_raw.config(0, (uint16_t)speed);
 	return versaloon_interface.adaptors.peripheral_commit();