Show usage on invalid command

Instead of instructing to re-run with -h, just show the usage help.

Signed-off-by: Andreas Färber <afaerber@suse.de>

main.cpp

@@ -2235,7 +2235,8 @@ bool handle_command(int argc, char* argv[], CRKScan *pScan)
 			}
 		}
 	} else {
-		printf("command is invalid, please run %s -h to check usage!\r\n", argv[0]);
+		printf("command is invalid!\r\n");
+		usage();
 	}
 	return bSuccess;
 }