net: wifi: shell: Correction to connect command default case

For default case it should print the option character provided by user.
Extra shell_help removed as it's being called in the caller function.

Signed-off-by: Ajay Parida <ajay.parida@nordicsemi.no>

subsys/net/l2/wifi/wifi_shell.c

@@ -584,8 +584,7 @@ static int __wifi_args_to_params(const struct shell *sh, size_t argc, char *argv
 		case 'h':
 			return -ENOEXEC;
 		default:
-			PR_ERROR("Invalid option %c\n", opt);
-			shell_help(sh);
+			PR_ERROR("Invalid option %c\n", optopt);
 			return -EINVAL;
 		}
 	}