irqchip/gic-v4: Correctly deal with set_affinity on lazily-mapped VPEs

irqchip/gic-v4: Correctly deal with set_affinity on lazily-mapped VPEs

Zenghui points out that a recent change to the way set_affinity is
handled for VPEs has the potential to return an error if the VPE
hasn't been mapped yet (because the guest hasn't emited a MAPTI
command yet), affecting GICv4.0 implementations that rely on the
ITSList feature.

Fix this by making the set_affinity succeed in this case, and
return early, without trying to touch the HW.

Fixes: 1442ee0011983 ("irqchip/gic-v4: Don't allow a VMOVP on a dying VPE")
Reported-by: Zenghui Yu <[email protected]>
Signed-off-by: Marc Zyngier <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Zenghui Yu <[email protected]>
Link: https://lore.kernel.org/all/[email protected]
Link: https://lore.kernel.org/r/[email protected]