MFC r256814, r256816, r256818, r256846, r256855, r256864 (by nwhitehorn):

- Handle 2GB of ram
- Allow the OFW interrupt mapping code to work with PCI devices not
enumerated by Open Firmware, as in the case of FDT.
- Provide an interface for PCI bus drivers that need some of ofw_pci's
metadata during attach.
- Use standard ofw_bus helpers instead of reinventing the wheel.
- Make hard-wired TLB allocations be at minimum one page.

MFC r256792, r256793, r256799 (by nwhitehorn): Unify AIM and booke code.

MFC r256814, r256816, r256818, r256846, r256855, r256864 (by nwhitehorn):

- Handle 2GB of ram
- Allow the OFW interrupt mapping code to work with PCI devices not
enumerated by Open Firmware, as in the case of FDT.
- Provide an interface for PCI bus drivers that need some of ofw_pci's
metadata during attach.
- Use standard ofw_bus helpers instead of reinventing the wheel.
- Make hard-wired TLB allocations be at minimum one page.

MFC r256792, r256793, r256799 (by nwhitehorn): Unify AIM and booke code.