net/ibmvnic: Cleanup workaround doing an EOI after partition migration

There were a fair amount of changes to workaround a firmware bug leaving
a pending interrupt after migration of the ibmvnic device :

commit 2df5c60e ("net/ibmvnic: Ignore H_FUNCTION return from H_EOI
       		    to tolerate XIVE mode")
commit 284f87d2 ("Revert "net/ibmvnic: Fix EOI when running in
       		    XIVE mode"")
commit 11d49ce9 ("net/ibmvnic: Fix EOI when running in XIVE mode.")
commit f23e0643 ("ibmvnic: Clear pending interrupt after device reset")

Here is the final one taking into account the XIVE interrupt mode.

Cc: Sukadev Bhattiprolu <sukadev@linux.ibm.com>
Cc: Dany Madden <drt@linux.ibm.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: David S. Miller <davem@davemloft.net>