boards: nucleo_l073rz: zephyr,entropy chosen already defined

Chosen `zephyr,entropy` is already defined in .dtsi file (as no other
source other than rng can be selected).

Signed-off-by: Erwan Gouriou <[email protected]>

Author: erwango

boards/arm/nucleo_l073rz/nucleo_l073rz.dts

@@ -18,7 +18,6 @@
 		zephyr,shell-uart = &usart2;
 		zephyr,sram = &sram0;
 		zephyr,flash = &flash0;
-		zephyr,entropy = &rng;
 	};
 
 	leds {