perf/x86/intel: Allow PEBS multi-entry in watermark mode

perf/x86/intel: Allow PEBS multi-entry in watermark mode

This patch fixes a restriction/bug introduced by:

   583feb08e7f7 ("perf/x86/intel: Fix handling of wakeup_events for multi-entry PEBS")

The original patch prevented using multi-entry PEBS when wakeup_events != 0.
However given that wakeup_events is part of a union with wakeup_watermark, it
means that in watermark mode, PEBS multi-entry is also disabled which is not the
intent. This patch fixes this by checking is watermark mode is enabled.

Signed-off-by: Stephane Eranian <eranian@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: jolsa@redhat.com
Cc: kan.liang@intel.com
Cc: vincent.weaver@maine.edu
Fixes: 583feb08e7f7 ("perf/x86/intel: Fix handling of wakeup_events for multi-entry PEBS")
Link: http://lkml.kernel.org/r/20190514003400.224340-1-eranian@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>