zsock_poll also supports eventfd (documentation)

[bdunlay]

Describe the bug
zsock_poll documentation states:

(In Zephyr this function works only with sockets, not arbitrary file descriptors.)

https://docs.zephyrproject.org/3.3.0/connectivity/networking/api/sockets.html#c.zsock_poll

poll() appears to also support the eventfd event source (#22863). I have used both socket fd and eventfd together in poll successfully.

Expected behavior
If eventfd is an officially supported event source for zsock_poll, the documentation should say so.

Impact
Misleading / confusing docs.

Environment (please complete the following information):

• Version used: Zephyr 3.3.0

[henrikbrixandersen]

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