test/poll-many: ensure 'nfiles' doesn't exceed NFILES

Fixes: 50342564de66 ("test/poll-many: make the test behave a bit better with file limits")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/test/poll-many.c b/test/poll-many.c
index 84de976..4f9ce02 100644
--- a/test/poll-many.c
+++ b/test/poll-many.c
@@ -173,6 +173,8 @@
 	if (rlim.rlim_cur < (2 * NFILES + 5)) {
 		rlim.rlim_cur = rlim.rlim_max;
 		nfiles = (rlim.rlim_cur / 2) - 5;
+		if (nfiles > NFILES)
+			nfiles = NFILES;
 		if (nfiles <= 0)
 			goto err_nofail;
 		if (setrlimit(RLIMIT_NOFILE, &rlim) < 0) {