power: mfd: k3_avs: update am65xx MPU_VDD voltage values

The latest data manual SPRSP08I –NOVEMBER 2017–REVISED DECEMBER 2019[1]
for am65xx SoC states the new MPU nominal voltages to be 1.1V (OPP_NOM),
1.2V (OPP_OD) and 1.24V (OPP_TURBO). Update the nominal voltages in the
K3 AVS driver to reflect this.

[1] http://www.ti.com/lit/gpn/am6528



Signed-off-by: Tero Kristo <t-kristo@ti.com>