Generic Xtensa target config files

- Add new Xtensa TCL board files
- Add new Xtensa KC705 on-board FTDI interface
- Add new generic Xtensa and VDebug Xtensa target files

Signed-off-by: Ian Thompson <ianst@cadence.com>
Change-Id: I4acb15c83d1b7b8e6063833ce829530cb22a795e
Reviewed-on: https://review.openocd.org/c/openocd/+/7083
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>

tcl/board/xtensa-palladium-vdebug.cfg

@@ -0,0 +1,16 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Cadence virtual debug interface
+# for Palladium emulation systems
+#
+
+source [find interface/vdebug.cfg]
+
+# vdebug select JTAG transport
+transport select jtag
+
+# JTAG reset config, frequency and reset delay
+reset_config trst_and_srst
+adapter speed 50000
+adapter srst delay 5
+
+source [find target/vd_xtensa_jtag.cfg]