mfd: Initial support for twl5031

TWL5031 introduces two new interrupts in PIH. Moreover, BCI
has changed remarkably and, thus, it's disabled when TWL5031
is in use.

Signed-off-by: Ilkka Koskinen <ilkka.koskinen@nokia.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>