During integration testing in Landau, it was discovered that a freshly unboxed reference hardware unit would sometimes boot what seemed to be a quite old test image from its onboard eMMC instead of booting from the SD card.  This turns out to be a symptom of the reference hardware devicetree not matching the addition of MMC device aliases done by the other Renesas boards in the kernel in 5.10.  The reason that is required is due to the MMC probe order becoming less deterministic in 5.10 with a switch to asynchronous probing (in upstream mainline commit 7320915c8861, for more details see the Renesas devicetree updates in d765a4f3 in mainline).  My belief is the presence of a filesystem on the on-board eMMC slightly affects the timing of the inherent race without the aliases present, on the other boards the eMMC is likely empty and things end up a bit more deterministic with respect to the order.  To avoid the possibility of intermittent issues and make using the on-board eMMC robust, the required aliases need to be added.