Hey,


This patch enables FEAT_DEBUGv8p9 extension for AArch64 and adds its 
system registers. FEAT_DEBUGv8p9 is default from Armv8.9-A Architecture.


Did regression testing for aarch64-none-elf target and found no regressions.


Ok for master? I don't have commit access so I need someone to commit on 
my behalf.


Regards,

Saurabh