ab8500_bm: Always send platform specific battery information via pdata

Currently the AB8500 battery management subsystem receives platform
specific information via two different means depending on how the
platform is booted. If DT is not enabled, a reference to a *_bm_data
data structure containing each platform specific attribute is passed
though platform_data. However, if DT is enabled, then platform_data
is empty and the reference is gained though a DT specific probe
function. There are two issues here 1) the same reference is
being collected each time and 2) the DT way doesn't allow any
provisions to select different platform specific attributes, which
kind of defeats the object.

Cc: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>