adapter: Deprecate Amontec JTAG Accelerator driver

The adapter is not available for years now and Amontec is not even a
company anymore. The poor hardware availability and the lack of users
prevents testing, maintenance and adaptations to future changes.

Mark the adapter as deprecated as a first step to give potential users
the opportunity to upgrade the hardware until the next OpenOCD release.

Change-Id: Idd9fb75588246bc39e12ea17a71435ed77f0f50b
Signed-off-by: Marc Schink <dev@zapb.de>
Reviewed-on: https://review.openocd.org/c/openocd/+/8349
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
Tested-by: jenkins

src/jtag/drivers/amt_jtagaccel.c

@@ -419,6 +419,8 @@ static int amt_jtagaccel_init(void)
 #endif
 	uint8_t ar_status;
 
+	LOG_WARNING("This adapter is deprecated and support will be removed in the next release!");
+
 #if PARPORT_USE_PPDEV == 1
 	if (device_handle > 0) {
 		LOG_ERROR("device is already opened");