uloop: remove useless epoll data assignment

ev.data is a union, so setting ev.data.fd is lost after setting
ev.data.ptr

Reported-by: Song Yaofei <songyaofei@joyware.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

uloop-epoll.c

@@ -52,7 +52,6 @@ static int register_poll(struct uloop_fd *fd, unsigned int flags)
 	if (flags & ULOOP_EDGE_TRIGGER)
 		ev.events |= EPOLLET;
 
-	ev.data.fd = fd->fd;
 	ev.data.ptr = fd;
 	fd->flags = flags;