mfd: Remove leftover from discontinued TWL4030 battery patch

The TWL4030_BCI_BATTERY config option originates from a patch to the
omap git tree. However inclusion in linux was seemingly rejected and
the functionality nears inclusion under a different name so this
removes the bits of the old version that made it into the mainline
kernel again.

Signed-off-by: Christoph Egger <siccegge@stud.informatik.uni-erlangen.de>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>