[TF-A] Run BL33 (u-boot) in EL3

Hi,

I'm maintaining TF-A for Intel SoCFPGA platform. Would it be possible if we should have the option to run BL33 (u-boot in our case) in EL3?

The Intel SoCFPGA platform u-boot used to handle all SMC calls: SPL u-boot (EL3) -> u-boot (EL3) And we have since move to use TF-A's BL31, thus boot became SPL u-boot (EL3) -> TF-A BL31 (EL3) -> u-boot (EL2)

Main reason is that some users would like to keep u-boot at EL3 as they do not care about security, and some users wanted to run some debugging read/write to secure region in u-boot shell.

Thanks Tien Hock