xen/events: reduce externally visible helper functions

xen/events: reduce externally visible helper functions

[ Upstream commit 686464514fbebb6c8de4415238319e414c3500a4 ]

get_evtchn_to_irq() has only one external user while irq_from_evtchn()
provides the same functionality and is exported for a wider user base.
Modify the only external user of get_evtchn_to_irq() to use
irq_from_evtchn() instead and make get_evtchn_to_irq() static.

evtchn_from_irq() and irq_from_virq() have a single external user and
can easily be combined to a new helper irq_evtchn_from_virq() allowing
to drop irq_from_virq() and to make evtchn_from_irq() static.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Stable-dep-of: fa765c4b4aed ("xen/events: close evtchn after mapping cleanup")
Signed-off-by: Sasha Levin <sashal@kernel.org>