Add new pmap code.
Fix handling of direct section unmapping.
    Use local variant of tlb_fush functions where appropriate
Merge r271716
Rename pmap_tlb_flush_page. Use correct argument type  when calling tlb_flush functions. Minor cleanup nits.
Switch DMA coherent memory to normal uncacheable memory
Major cleanup of new pmap code.
Fix comments. Use macro for simplify pvh list Add first managed physical address.
Fix style.
Use new VM_PHYSSEG_SPARSE infrastructure
Use global tlb flush when servicing emulated access and modified bits.
Adjust NKPT2PG. Fix improper usage of ATTR_TO_L2. Add comments in pmap_init().
Remove now useless .arch directive form assembler files.
Fix checking for current pmap. Remove obsolete header.
Fix bogus constant for shift. Don't set cached flag in TTB for CPUs that not support cached page table walk.
As per Alan L. Cox recommendation, remove lazy switch.
Make ofwbus as a subclass of simplebus. Remove bogus checking for busy resource.
Remove now duplicated code from ofwbus.c. Move all useful methods into simplebus.c.
Move resource managers for IRQ and memory from ofwbus to nexus.
Other code uses 0 for invalid phandle, so use it in simplebus_get_devinfo() too.
Rename Exynos UART. No functional change.
Don't use C++ reserved word "class" in uart_cpu_fdt.c. No functional change.