bios takeover was broken. bad Ceecpmask (was 8, should be 0xFF)
causing it to miss the legacy control ecap and properly take
overship of the controller. also the order seems wrong, we
have to takeover before we do anything with the controller.
remove the pci config space 0xc0 = 0x2000 write. this the
uhci legacy register. its not anywhere in the ehci spec.
sometimes, the bios does not assign a interrupt line for pci
devices. this should not be fatal in case of mp ineterrupts
as long as there is intpin or msi can be used.
warn in intrenable() if we hit such a interrupt and set
irq to -1 to prevent it from getting enabled on the pic
or as isa interrupt in apic mode.
