steering: suppress ENOENT error messages

If we did not bandsteer a client, failure to remove
the steering files is expected.

chdir(/tmp/wifi/steering/2.4_bf13157e13): No such file or directory
Garbage collecting steering timestamp files failed: No such file or directory

Change-Id: I0b474a367bcf5c2eea38dbce0125c07018375539
diff --git a/src/ap/steering.c b/src/ap/steering.c
index bb87dca..f26c90e 100644
--- a/src/ap/steering.c
+++ b/src/ap/steering.c
@@ -216,9 +216,13 @@
 	}
 
 	if (chdir(request_logging_path) == -1) {
-		wpa_printf(MSG_ERROR, "chdir(%s): %s",
-		           request_logging_path, strerror(errno));
-		return -1;
+		if (errno != ENOENT) {
+			wpa_printf(MSG_ERROR, "chdir(%s): %s",
+			           request_logging_path, strerror(errno));
+			return -1;
+		} else {
+			return 0;
+		}
 	}
 
 	num_timestamp_files = scandir(request_logging_path, &namelist,