drivers: flash: stm32h7: do not unlock CR at the end of init

Do not unlock CR at the end of initialization.

The lock mechanism is to protect unwanted registers modifications due to
software bugs. There is no point in leaving the registers unlock once
the driver is initialized.

Signed-off-by: Dawid Niedzwiecki <dawidn@google.com>

drivers/flash/flash_stm32h7x.c

@@ -767,7 +767,7 @@ static int stm32h7_flash_init(const struct device *dev)
 	}
 #endif
 
-	return flash_stm32h7_write_protection(dev, false);
+	return 0;
 }
 
 DEVICE_DT_INST_DEFINE(0, stm32h7_flash_init, NULL, &flash_data, NULL, POST_KERNEL,