perf: Completely remove possibility to override MAX_NR_CPUS

Commit 21b8732e ("perf tools: Allow overriding MAX_NR_CPUS at
compile time") added the capability to override MAX_NR_CPUS. At
that time it was necessary to reduce the huge amount of RAM used
by static stats variables.

But this has been unnecessary since commit 6a1e2c5c ("perf stat:
Remove a set of shadow stats static variables"), and
commit e8399d34 ("libperf cpumap: Hide/reduce scope of
MAX_NR_CPUS") broke the build in that case because it failed to
add the guard around the new definition of MAX_NR_CPUS.

So cleanup things and remove guards completely to officialise it
is not necessary anymore to override MAX_NR_CPUS.

Fixes: e8399d34 ("libperf cpumap: Hide/reduce scope of MAX_NR_CPUS")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/all/8c8553387ebf904a9e5a93eaf643cb01164d9fb3.1736188471.git.christophe.leroy@csgroup.eu/


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>