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)

Don't expose the uart_ops structure directly, but instead have
it obtained through the uart_class structure. This allows us
to declare the uart_class structure as weak and as such allows
us to reference it even when it's not compiled-in.
It also allows is to get the uart_ops structure by name, which
makes it possible to implement the dt tag handling in uart_getenv().
The side-effect of all this is that we're using the uart_class
structure more consistently which means that we now also have
access to the size of the bus space block needed by the hardware
when we map the bus space, eliminating any hardcoding.

Don't forget to define uart_sa1110_vaddr.

Submitted by: kevlo

Now that we use pmap_mapdev_boostrap(), we can get ride of the got_mmu
hack.

Submitted by: kevlo

Use pmap_devmap_bootstrap(), instead of mapping the SACOM1 registers
with pmap_map_entry.
More use of macros instead of hardcoding the addr.

Submitted by: kevlo

Start all license statements with /*-

Define uart_sa1110_ops and uart_sa1110_classe in .c files instead of spamming
uart_cpu.h

Implement enough of an uart driver to get serial console working.