tcl/interface/ftdi: Add config for Tigard board

Tigard[1] is an FT2232H-based development tool designed for ease of use
with many different protocols and targets. It includes a JTAG header
wired to channel B, with labeled pins for the four required signals as
well as nTRST and nSRST, which are connected through an output buffer to
BDBUS4 and BDBUS5 respectively.

Add an interface config for Tigard. I wrote it by referencing the Tigard
schematic and tested it by debugging a couple of RISC-V development
boards.

[1] https://github.com/tigard-tools/tigard

Signed-off-by: Thomas Hebb <tommyhebb@gmail.com>
Change-Id: I34df9f72538ba1e40ad53b568c9cdca96ae4b082
Reviewed-on: https://review.openocd.org/c/openocd/+/6952
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>

tcl/interface/ftdi/tigard.cfg

@@ -0,0 +1,19 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+#
+# Tigard: An FTDI FT2232H-based multi-protocol tool for hardware hacking.
+# https://github.com/tigard-tools/tigard
+
+adapter driver ftdi
+
+ftdi device_desc "Tigard V1.1"
+ftdi vid_pid 0x0403 0x6010
+
+ftdi channel 1
+
+ftdi layout_init 0x0038 0x003b
+ftdi layout_signal nTRST -data 0x0010
+ftdi layout_signal nSRST -data 0x0020
+
+# This board doesn't support open-drain reset modes since its output buffer is
+# always enabled.
+reset_config srst_push_pull trst_push_pull