When using Zephyr, we also want to use the proper wc_GenerateSeed method. However, if one of the defines is set (e.g., NO_STM32_RNG), the Zephyr option is ignored, although it would work. Hence, we have to change the order in which these settings for the source of a random seed are evaluated. Signed-off-by: Tobias Frauenschläger <t.frauenschlaeger@me.com>