cfg: Add interface config for Dangerous Prototypes Bus Blaster

This is a FT2232 based USB JTAG dongle

Change-Id: Ibed773a23b6446df62fe4eac16c27fb2d741f4c3
Signed-off-by: Allen Martin <amartin@nvidia.com>
Reviewed-on: http://openocd.zylin.com/589
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>

tcl/interface/busblaster.cfg

@@ -0,0 +1,10 @@
+#
+# Dangerous Prototypes Bus Blaster
+#
+# http://dangerousprototypes.com/
+#
+
+interface ft2232
+ft2232_vid_pid 0x0403 0x6010
+ft2232_device_desc "Dual RS232-HS"
+ft2232_layout jtagkey