riscv: dts: sifive unmatched: Link the tmp451 with its power supply

Fixes the following probe warning:
  lm90 0-004c: Looking up vcc-supply from device tree
  lm90 0-004c: Looking up vcc-supply property in node /soc/i2c@10030000/temperature-sensor@4c failed
  lm90 0-004c: supply vcc not found, using dummy regulator
Signed-off-by: NVincent Pelletier <plr.vincent@gmail.com>
Signed-off-by: NPalmer Dabbelt <palmer@rivosinc.com>

arch/riscv/boot/dts/sifive/hifive-unmatched-a00.dts

@@ -55,6 +55,7 @@
 	temperature-sensor@4c {
 		compatible = "ti,tmp451";
 		reg = <0x4c>;
+		vcc-supply = <&vdd_bpro>;
 		interrupt-parent = <&gpio>;
 		interrupts = <6 IRQ_TYPE_LEVEL_LOW>;
 	};