Added new ftdi interface device

Added new configuration file for gw16042 device.
Also added this to interface/ftdi examples in documentation.

Change-Id: I07bb10bfc79a5d13007288cd57f254d889075214
Signed-off-by: Pushpal Sidhu <psidhu@gateworks.com>
Reviewed-on: http://openocd.zylin.com/1563
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>

tcl/interface/ftdi/gw16042.cfg

@@ -0,0 +1,26 @@
+#
+# Gateworks GW16042 JTAG Dongle
+#
+# http://www.gateworks.com/
+#
+# Layout:  FTDI FT2232H
+#   ADBUS0 TCK
+#   ADBUS1 TDI
+#   ADBUS2 TDO (input)
+#   ADBUS3 TMS
+#   ADBUS4 nTRST
+#   ADBUS5 nSRST
+#   ADBUS6 OE (active high) for TRST, TDI, TMS, TCK
+#   ADBUS7 NC
+#   ACBUS0-7 NC
+#   BDBUS0 RXD
+#   BDBUS1 TXD (input)
+#
+
+interface ftdi
+ftdi_device_desc "USB-JTAG"
+ftdi_vid_pid 0x0403 0x6010
+
+ftdi_layout_init 0x0058 0x007b
+ftdi_layout_signal nTRST -data 0x0010
+ftdi_layout_signal nSRST -oe 0x0020