ti_icdi: add icdi_usb_query result check

Change-Id: I0b40586677a77ee6ae46fe120a677616bde22d1e
Signed-off-by: Spencer Oliver <spen@spen-soft.co.uk>
Reviewed-on: http://openocd.zylin.com/1279
Tested-by: jenkins
Reviewed-by: Xiaofan <xiaofanc@gmail.com>
Reviewed-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>

src/jtag/drivers/ti_icdi_usb.c

@@ -385,6 +385,8 @@ static int icdi_usb_query(void *handle)
 
 	/* set extended mode */
 	result = icdi_send_cmd(handle, "!");
+	if (result != ERROR_OK)
+		return result;
 
 	/* check result */
 	result = icdi_get_cmd_result(handle);