perf vendor events arm64: Remove [[:xdigit:]] wildcard

ARM64's implementation of get_cpuidr_str() masks out the revision bits
[3:0] while reading the CPU identifier, there is no need for the
[[:xdigit:]] wildcard.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: John Garry <john.garry@huawei.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sean V Kelley <seanvk.dev@oregontracks.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-arm-kernel@lists.infradead.org (moderated list:arm pmu profiling and debugging)
Link: http://lkml.kernel.org/r/20190513202522.9050-2-f.fainelli@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>