Add support for Bus Pirate as a JTAG adapter.

This includes a driver and matching config file.  This support needs to be
enabled through the initial "configure" (use "--enable-buspirate").

Signed-off-by: Michal Demin <michaldemin@gmail.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>

tcl/interface/buspirate.cfg

@@ -0,0 +1,26 @@
+#
+# Buspirate with OpenOCD support
+#
+# http://dangerousprototypes.com/bus-pirate-manual/
+#
+
+interface buspirate
+
+# you need to specify port on which BP lives
+#buspirate_port /dev/ttyUSB0
+
+# communication speed setting
+buspirate_speed normal # or fast
+
+# voltage regulator Enabled = 1 Disabled = 0
+#buspirate_vreg 0
+
+# pin mode normal or open-drain
+#buspirate_mode normal
+
+# pullup state Enabled = 1 Disabled = 0
+#buspirate_pullup 0
+
+# this depends on the cable, you are safe with this option
+reset_config srst_only
+