pirq_cleanup_check() leaks

pirq_cleanup_check() leaks

Its original introduction had two issues: For one the "common" part of
the checks (carried out in the macro) was inverted. And then after
removal from the radix tree the structure wasn't scheduled for freeing.
(All structures still left in the radix tree would be freed upon domain
destruction, though.)

For the freeing to be safe even if it didn't use RCU (i.e. to avoid use-
after-free), re-arrange checks/operations in evtchn_close(), such that
the pointer wouldn't be used anymore after calling pirq_cleanup_check()
(noting that unmap_domain_pirq_emuirq() itself calls the function in the
success case).

Fixes: c24536b636f2 ("replace d->nr_pirqs sized arrays with radix tree")
Fixes: 79858fee307c ("xen: fix hvm_domain_use_pirq's behavior")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Release-Acked-By: Oleksii Kurochko <oleksii.kurochko@gmail.com>