There is a huge number of broken device trees out there. Just
grepping through the tree for the use of IRQ_TYPE_NONE in conjunction
with the GIC is scary.

People just don't realise that IRQ_TYPE_NONE just doesn't exist, and
you just get whatever junk was there before. So let's make them aware
of the issue.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>