Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Let simplebus(4) diagnostics be a bit more descriptive.

Import the common Flattened Device Tree infrastructure.

o fdtbus(4) - the main abstract bus driver for all FDT-compliant systems. This
is a direct replacement for the many incompatible bus drivers grouping
integrated peripherals on embedded platforms (like obio(4), ocpbus(4) etc.)

o simplebus(4) - bus driver representing ePAPR style 'simple-bus' node, which
is an umbrella device for most of the integrated peripherals on a typical
system-on-chip device.

o Other components (common routines library, PCI node processing helper
functions)

Reviewed by: imp
Sponsored by: The FreeBSD Foundation