perf: Fix broken union in 'struct perf_event_mmap_page'

The capabilities bits must not be "union'ed" together.
Put them in a separate struct.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1372425741-1676-2-git-send-email-adrian.hunter@intel.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>