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)

- Rename ds1672 and ds133x devices to "ds1672_rtc" and "ds133x_rtc"
respectivly. This will allow one to have a kernel with both devices
present and use it for multiple boards with different types of RTC
sitting on a bus.

Discussed with: imp

- Give a warning and start the oscillator if it was not previously
runned.
- Rename ds1672 -> rtc to follow the other drivers.
- Refactor/simplify the code a bit.

MFC after: 2 weeks

Change the way I2C bus attachment works to allow firmware-assisted bus
subclasses as are available with PCI. Changes I2C device drivers without
real probe logic to return BUS_PROBE_NOWILDWARD to avoid interference with
firmware bus enumeration, and reduces the probe priority of the iicbus
base driver to allow subclass attachment at higher priority.

Discussed on: freebsd-arch

Streamline #include sections in ds133x and ds1672 drivers. This unbreaks the
LINT build.

i2c and clock driver for Dallas Semiconductor DS1672 RTC

MFC after: 1 month