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/target/dsp563xx.c

@@ -2243,7 +2243,7 @@ static const struct command_registration dsp563xx_command_handlers[] = {
 		.handler = dsp563xx_remove_watchpoint_command,
 		.mode = COMMAND_EXEC,
 		.help = "remove watchpoint custom",
-		.usage = " ",
+		.usage = "",
 	},
 	COMMAND_REGISTRATION_DONE
 };