ARM: dts: stm32: Add romem and temperature calibration on stm32mp157c

Add & enable stm32 factory-programmed memory. Describe temperature sensor
calibration cells. Non-volatile calibration data is made available by
stm32mp157c bootrom in bsec_dataX registers.
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>

arch/arm/boot/dts/stm32mp157c.dtsi

@@ -1229,6 +1229,19 @@ rtc: rtc@5c004000 {
 			status = "disabled";
 		};
 
+		bsec: nvmem@5c005000 {
+			compatible = "st,stm32mp15-bsec";
+			reg = <0x5c005000 0x400>;
+			#address-cells = <1>;
+			#size-cells = <1>;
+			ts_cal1: calib@5c {
+				reg = <0x5c 0x2>;
+			};
+			ts_cal2: calib@5e {
+				reg = <0x5e 0x2>;
+			};
+		};
+
 		i2c6: i2c@5c009000 {
 			compatible = "st,stm32f7-i2c";
 			reg = <0x5c009000 0x400>;