regulator: tps65910: Configure correct value for VDDCTRL vout reg

As per datasheet, the voltage output is defined as
from SEL[6:0] = 3 to 64 (dec)
Vout= (SEL[6:0] × 12.5 mV + 562.5 mV)

The list_voltage returns the vout as
    600mV +  selector * 12.5mV

and so equivalent VSEL is selector + 3.
Adding 3 on selector when configuring VSEL register for
VDDCTRL output.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>