CPU_CYCLES counter does not work on some Aarch64 CPUs; CYCLES is more
generic and is equivalent to CPU_CYCLES in case the latter is supported.
Longer story - CPU_CYCLES work only on CPU models explicitly recognized
by libpfm4 ( via pfm_arm_detect_*() functions in
https://sourceforge.net/p/perfmon2/libpfm4/ci/master/tree/lib/pfmlib_arm_armv8.c
) and its name is consistent with ARM documentation. However, the
counter is architectural and is supported on all ARMv8 CPUs; libpfm4
recognizes generic PMU on unknown ARMv8 CPUs, but does not provide
CPU_CYCLES event. Instead, CYCLES is provided (an alias to
PERF_COUNT_HW_CPU_CYCLES). Physically, it is the same event with code
0x11. On supported architectures CYCLES also work, so the change should
not introduce regression.
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