KVM: arm64: vgic-its: Test for valid IRQ in MOVALL handler

It is possible that an LPI mapped in a different ITS gets unmapped while
handling the MOVALL command. If that is the case, there is no state that
can be migrated to the destination. Silently ignore it and continue
migrating other LPIs.

Cc: stable@vger.kernel.org
Fixes: ff9c1143 ("KVM: arm/arm64: GICv4: Handle MOVALL applied to a vPE")
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240221092732.4126848-3-oliver.upton@linux.dev


Signed-off-by: Marc Zyngier <maz@kernel.org>