We used to use performance cycle counter for cycles(),
but it is kind of useless in userspace as each core
has its own counter and hence not comparable between
cores. Also, the cycle counter stops counting when
the cores are idle.
Most callers expect cycles() to return a high resolution
timestamp instead, so do the best we can do here
and enable the userspace generic timer virtual counter.
the raspberry pi 4 has a new interrupt controller and
pci support, so get rid of intrenable() macro and
properly make intrenable function with tbdf argument.
cinap_lenrek