[Hafnium] FFA_CONSOLE_LOG control characters filtering

Hi,

I noticed Hafnium's FFA_CONSOLE_LOG implementation permits writing any ascii character to the UART.

In particular the StMM/EDKII print library explicitly adds <CR> characters on any output string, however those are not interpreted by the implementation and directly sent to the UART driver (as opposed to <LF> https://review.trustedfirmware.org/plugins/gitiles/hafnium/hafnium/+/refs/he... ) .

Is it fair adding filtering to omit control characters https://review.trustedfirmware.org/c/hafnium/hafnium/+/27265/2/src/api.c#443... ?

Regards, Olivier.