perf top: Error handling for counter creation should parallel perf-record

perf top: Error handling for counter creation should parallel perf-record

708aaf8 fixed up perf-record but not perf-top. Similar argument holds
for it -- fallback to PMU only if it does not exist and handle invalid
attributes separately.

Signed-off-by: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Robert Richter <robert.richter@amd.com>
Link: http://lkml.kernel.org/r/1343616783-6360-1-git-send-email-dsahern@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>