arm64: perf: Correct Cortex-A53/A57 compatible values

Use commas instead of periods.

Acked-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Dirk Behme <dirk.behme@gmail.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Will Deacon <will.deacon@arm.com>