Change return value on error.

On wrong parameters a error is signalized to the calling function.

Change-Id: I484443fdb39938e20382edc9246d5ec546a5c960
Signed-off-by: Mathias K <kesmtp@freenet.de>
Signed-off-by: Øyvind Harboe <oyvind.harboe@zylin.com>
Reviewed-on: http://openocd.zylin.com/282
Tested-by: jenkins
Reviewed-by: Øyvind Harboe <oyvindharboe@gmail.com>

src/target/target_request.c

@@ -302,7 +302,7 @@ COMMAND_HANDLER(handle_target_request_debugmsgs_command)
 		}
 		else
 		{
-			command_print(CMD_CTX, "usage: target_request debugmsgs ['enable'|'disable'|'charmsg']");
+		    return ERROR_COMMAND_SYNTAX_ERROR;
 		}
 	}