perf mmap: Add missing bitops.h header

perf mmap: Add missing bitops.h header

MMAP_CPU_MASK_BYTES uses the BITS_TO_LONGS macro, which is defined in
linux/bitops.h.

However, this header is not included directly, but gets imported
indirectly in files using the macro.

This patch adds the missing include.

Signed-off-by: Riccardo Mancini <rickyman7@gmail.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/c5b91ee432a2e28e7f16337c740b43b4d0b0e86c.1629490974.git.rickyman7@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>