Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

strict kobj signatures: fix iicbus_write impl in dev/pcf

input buf is const

Reviewed by: imp, current@
Approved by: jhb (mentor)

Add locking to the various iicbus(4) bridge drivers:
- Just grab Giant in the ixp425_iic(4) driver since this driver uses
a shared address/data register window pair to access the actual
I2C registers. None of the other ixp425 drivers lock access to these
shared address/data registers yet and that would need to be done before
this could use any meaningful locking.
- Add locking to the interrupt handler and 'iicbus_reset' methods of the
at91_twi(4) driver.
- Add locking to the pcf(4) driver. Other pcf(4) fixes include:
- Don't needlessly zero the softc.
- Use bus_foo rather than bus_space_foo and remove bus space tag and
handle from softc.
- The lpbb(4) driver just grabs Giant for now. This will be refined later
when ppbus(4) is locked.
- As was done with smbus earlier, move the DRIVER_MODULE() lines to match
the bus driver (either iicbus or iicbb) to the bridge driver into the
bridge drivers.

Tested by: sam (arm/ixp425)

Unbreak after struct resource was hidden. Tested with EBus front-end on
Sun AXe board.

Consistently use __inline instead of __inline__ as the former is an empty macro
in <sys/cdefs.h> for compilers without support for inline.

Round #1 of improving pcf(4).

This splits the driver into a bus-independant backend, plus bus-specific
frontends. The old pcf(4) (i386/ISA) frontend is now in pcf_isa.c, the
frontend in envctrl.c is for sparc64/Ebus2 (Sun device name: SUNW,envctrl
from Sun E450 machines). More frontends are expected to appear in future.

This is not yet ready for public consumption, but it basically works.
Nicolas will bring over his ISA-specific fixes soon.

Reviewed by: nsouch