Perf: arm64: Use all 6 counters in tracecounters

Tracecounter code was only displaying the values from the first
4 PMU counters. This patch will display all 6 PMU counter values.
Change output strings L2CTR0, L2CTR1 to CTR4, CTR5 respectively.

Change-Id: I111355513bf30a2544bf10e4fbfda79f4cf2678c
Signed-off-by: Patrick Fay <pfay@codeaurora.org>