ARM: dts: at91: sam9x60ek: modify vdd_1v5 regulator to vdd_1v15

This regulator is powering the vddcore pins from MPU.
Its real value on the board and in the MPU datasheet is 1.15V.

Signed-off-by: Mihai Sain <mihai.sain@microchip.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20220302160235.28336-1-nicolas.ferre@microchip.com