perf symbols: symbol inconsistency message should be done only at verbose=1

That happened for an old perf.data file that had no fake MMAP events for
the kernel modules, but even then it should warn once for each module,
not one time for every symbol in every module not found.

Reported-by: Ingo Molnar <mingo@elte.hu>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>