mfd: lp87565: Add support for 4-phase LP87561 combination

Add support for 4-phase LP87561 combination.

Data Sheet: https://www.ti.com/lit/ds/symlink/lp87561-q1.pdf



Signed-off-by: Keerthy <j-keerthy@ti.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>