drivers/presto: Group adapter commands

Use a command group 'presto' with subcommands instead of individual
commands with 'presto_' prefix.

The old commands are still available for backward compatibility but
marked as deprecated.

Change-Id: I883d8d87fd457d29cee8d12cd80f2e6c405e8f42
Signed-off-by: Marc Schink <dev@zapb.de>
Reviewed-on: http://openocd.zylin.com/6390
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>

src/jtag/startup.tcl

@@ -309,4 +309,10 @@ proc parport_toggling_time args {
 	eval parport toggling_time $args
 }
 
+lappend _telnet_autocomplete_skip presto_serial
+proc presto_serial args {
+	echo "DEPRECATED! use 'presto serial' not 'presto_serial'"
+	eval presto serial $args
+}
+
 # END MIGRATION AIDS