write_queue: Use EBADF instead of EBABDFD for portability

EBADFD is linux specific while EBADF is POSIX. Fix the build on
FreeBSD and use EBADF throughout the file.
diff --git a/src/write_queue.c b/src/write_queue.c
index 80e6c42..9a8b05c 100644
--- a/src/write_queue.c
+++ b/src/write_queue.c
@@ -46,13 +46,13 @@
 
 	if (what & BSC_FD_READ) {
 		rc = queue->read_cb(fd);
-		if (rc == -EBADFD)
+		if (rc == -EBADF)
 			goto err_badfd;
 	}
 
 	if (what & BSC_FD_EXCEPT) {
 		rc = queue->except_cb(fd);
-		if (rc == -EBADFD)
+		if (rc == -EBADF)
 			goto err_badfd;
 	}
 
@@ -69,7 +69,7 @@
 			rc = queue->write_cb(fd, msg);
 			msgb_free(msg);
 
-			if (rc == -EBADFD)
+			if (rc == -EBADF)
 				goto err_badfd;
 
 			if (!llist_empty(&queue->msg_queue))