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)

- Use macbstart_locked() directly instead of deferring it to a task.
- Expand locking scope in interrupt handler.
- Flesh out the detach routine.

Reviewed by: cognet

Converted the remainder of the NIC drivers to use the mii_attach()
introduced in r213878 instead of mii_phy_probe(). Unlike r213893 these
are only straight forward conversions though.

Reviewed by: yongari

if_ate.c:

* Support for sam9 "EMAC" controller.
* Support for rmii interface to phy.

at91.c & at91sam9.c:

* Eliminate separate at91sam9.c file.
* Add new devices to at91sam9_devs table.

at91_machdep.c & at at91sam9_machdep.c:

* Automatic chip type determination.
* Remove compile time chip dependencies.
* Eliminate separate at91sam9_machdep.c file.

at91_pmc.c:

* Corrected support for all of the sam926? and sam9g20 chips.
* Remove compile time chip dependencies.

My apologies to Greg for taking so long to take care of it.

Import preliminary support for Atmel AT91SAM9G20 cpu, and the Hot-e HL201.
This fine work was done by Yohanes Nugroho <yohanes a gmail dot com>
Many thanks to John Nicholls and Thinlinx for providing sample hardware.