s390x/pci: avoid double enable/disable of aif

s390x/pci: avoid double enable/disable of aif

Use a flag to keep track of whether AIF is currently enabled.  This can be
used to avoid enabling/disabling AIF multiple times as well as to determine
whether or not it should be disabled during reset processing.

Fixes: d0bc7091c2 ("s390x/pci: enable adapter event notification for interpreted devices")
Reported-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
Message-ID: <20240118185151.265329-2-mjrosato@linux.ibm.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
(cherry picked from commit 07b2c8e034d80ff92e202405c494d2ff80fcf848)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>