epoll: simplify ep_busy_loop by removing always 0 argument

epoll: simplify ep_busy_loop by removing always 0 argument

Commit 00b27634bc471("epoll: replace gotos with a proper loop") refactored
ep_poll and always feeds ep_busy_loop with a time_out value of 0, nonblock
mode for ep_busy_loop has sunk since, IOW nonblock mode checking has been
taken over by ep_poll itself, codes snipped:

static int ep_poll(struct eventpoll *ep...
{
...
    if (timed_out)
        return 0;

    eavail = ep_busy_loop(ep, timed_out);
...
}

Given this fact codes can be simplified a bit for ep_busy_loop.

Signed-off-by: Lin Feng <linf@wangsu.com>
Link: https://lore.kernel.org/r/20250227033412.5873-1-linf@wangsu.com
Signed-off-by: Christian Brauner <brauner@kernel.org>