examples: fix incorrect error message in fxload

* Closes #3
diff --git a/examples/fxload.c b/examples/fxload.c
index 9f0d554..f1d973b 100644
--- a/examples/fxload.c
+++ b/examples/fxload.c
@@ -147,7 +147,7 @@
 		return print_usage(-1);
 	}
 	if ((device_id != NULL) && (device_path != NULL)) {
-		logerror("only one of -d or -a can be specified\n");
+		logerror("only one of -d or -p can be specified\n");
 		return print_usage(-1);
 	}