implement stlink_usb_send and use it to fix stlink_usb_write_mem using two calls to stlink_usb_recv is inappropriate since each call issues a SG command on stlink-v1, resulting in errors Change-Id: I24ef9f2dda284e041dc4a532b59968a77eebe702 Signed-off-by: Szymon Modzelewski <szmodzelewski@gmail.com> Reviewed-on: http://openocd.zylin.com/498 Tested-by: jenkins Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>