[Hafnium] FFA_FEATURES and FFA_RXTX_MAP_64

Hi,

We noticed api_ffa_features returns FFA_SUCCESS_32 for all implemented ABIs with the SMC32 convention, but FFA_RXTX_MAP_64: https://git.trustedfirmware.org/hafnium/hafnium.git/tree/src/api.c#n1430

On the other hand ffa_handler discards the SMC convention bit: https://git.trustedfirmware.org/hafnium/hafnium.git/tree/src/arch/aarch64/hy...

It means one can call FFA_FEATURES(FFA_RXTX_MAP_32) which will fail, although this does not prevent effectively calling the same ABI with the SMC32 convention.

Is there some fine tuning to do here? Should we just discard the SMC convention bit in api_ffa_features?

Regards, Olivier.