eventpoll: Control irq suspension for prefer_busy_poll

eventpoll: Control irq suspension for prefer_busy_poll

When events are reported to userland and prefer_busy_poll is set, irqs
are temporarily suspended using napi_suspend_irqs.

If no events are found and ep_poll would go to sleep, irq suspension is
cancelled using napi_resume_irqs.

Signed-off-by: Martin Karsten <[email protected]>
Co-developed-by: Joe Damato <[email protected]>
Signed-off-by: Joe Damato <[email protected]>
Tested-by: Joe Damato <[email protected]>
Tested-by: Martin Karsten <[email protected]>
Acked-by: Stanislav Fomichev <[email protected]>
Reviewed-by: Sridhar Samudrala <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>