ARM: dts: stm32: add vrefint calibration on stm32mp15

Describe vrefint calibration cell to be retrieved through bsec.
Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>

arch/arm/boot/dts/stm32mp151.dtsi

@@ -1630,6 +1630,9 @@ bsec: efuse@5c005000 {
 			part_number_otp: part-number-otp@4 {
 				reg = <0x4 0x1>;
 			};
+			vrefint: vrefin-cal@52 {
+				reg = <0x52 0x2>;
+			};
 			ts_cal1: calib@5c {
 				reg = <0x5c 0x2>;
 			};