add another perf_name for ARM Cortex-A57

PAPI developers with NVIDIA Jetson board and ARM Cortex-A57
reported that the Linux PMU type is "armv8_pmuv3"
Add that name as a possible name to the list of perf_name
for Cortex A57.

Signed-off-by: Vince Weaver <vincent.weaver@maine.edu>