help text: remove trailing space

Some help text end with a useless space character.
Remove it.

Change-Id: I397e1194fac8042f0fab694222f925f906716de3
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/6222
Tested-by: jenkins

src/jtag/adapter.c

@@ -584,7 +584,7 @@ static const struct command_registration adapter_command_handlers[] = {
 		.handler = adapter_transports_command,
 		.mode = COMMAND_CONFIG,
 		.help = "Declare transports the adapter supports.",
-		.usage = "transport ... ",
+		.usage = "transport ...",
 	},
 	{
 		.name = "usb",