perf tools: Fix up some comments and code to properly use the event_source bus

In sysfs, the perf events are all located in
/sys/bus/event_source/devices/ but some places ended up hard-coding the
location to be at the root of /sys/devices/ which could be very risky as
you do not exactly know what type of device you are accessing in sysfs
at that location.

So fix this all up by properly pointing everything at the bus device
list instead of the root of the sysfs devices/ tree.

Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Link: https://lore.kernel.org/r/2025021955-implant-excavator-179d@gregkh


Signed-off-by: Namhyung Kim <namhyung@kernel.org>