if get_property("msi_available")
	mpic_msi_reserve_dt_irqs()

available-msi is a better name now that I think of it, or better even:
"msi-ranges"

elif is_u3_or_u4()
	mpic_msi_reserve_u3u4_irqs()
else
	return error

Because if we don't have a firmware property, and we don't make an
educated guess at what's reserved, then there's a very good chance our
first MSI will get hwirq 0 and that it won't work.

As far as putting hacks in the MPIC driver .. have you read it
lately? ;)  But seriously, I think if there's anyway these magic numbers
should be, it is in this code, not the platform code.

Ben.