irqchip: gicv3-its: Fix device ID encoding

When building ITS commands which have the device ID in it, we
should mask off the whole upper 32 bits of the first command word
before inserting the new value in there.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Link: https://lkml.kernel.org/r/1427465705-17126-3-git-send-email-marc.zyngier@arm.com


Signed-off-by: Jason Cooper <jason@lakedaemon.net>