eventpoll: Don't re-zero eventpoll fields

Remove redundant and unnecessary code.

ep_alloc uses kzalloc to create struct eventpoll, so there is no need to
set fields to defaults of 0. This was accidentally introduced in commit
85455c79 ("eventpoll: support busy poll per epoll instance") and
expanded on in follow-up commits.

Signed-off-by: Joe Damato <jdamato@fastly.com>
Link: https://lore.kernel.org/r/20240807105231.179158-1-jdamato@fastly.com


Reviewed-by: Martin Karsten <mkarsten@uwaterloo.ca>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>