[U-Boot] One u-boot.bin for Raspberry PI 3 and 4 - possible?

[Geoff Williams]

> And with a U-Boot based on f5c626c64874d6e1482edf4a76aa22e5e54be63d without my
> patches you see correct behavior?

The screen turning off issue was caused by a deployment script copying the wrong
u-boot binary to the SD card! The patch does not introduce a regression on RPI 3
(tested before/after patch).

Once I switched over to the the real u-boot image the grub graphical font didn't
load (irrespective of patch) I was able to fix this by changing the
rpi_3_defconfig:

-CONFIG_OF_EMBED=y
-CONFIG_DEFAULT_DEVICE_TREE="bcm2837-rpi-3-b"
+CONFIG_OF_BOARD=y

I suspect my issues are to do with DTBs and that all these problems will go away
once a single defconfig is available. The screen turning off issue I have no
idea about but its from a much older version of u-boot and probably relates to
something in the image I built.

Sorry for the noise - lets park this one.

Cheers,
Geoff