mfd: AB3100 register access change to abx500 API

The interface for the AB3100 is changed to make way for the
ABX500 family of chips: AB3550, AB5500 and future ST-Ericsson
Analog Baseband chips. The register access functions are moved
out to a separate struct abx500_ops. In this way the interface
is moved from the implementation and the sub functionality drivers
can keep their interface intact when chip infrastructure and
communication mechanisms changes. We also define the AB3550
device IDs and the AB3550 platform data struct and convert
the catenated 32bit event to an array of 3 x 8bits.

Signed-off-by: Mattias Wallin <mattias.wallin@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>