perf xyarray: Save max_x, max_y

Save the original array dimensions in xyarrays, so that users can
retrieve them later. Add some inline functions to access these fields.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/20170811232634.30465-1-andi@firstfloor.org
[ As noticed by Jiri, fix up namespacing: xy__method() -> xyarray__method() ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/xyarray.c b/tools/perf/util/xyarray.c
index 7251fdb..c8f415d 100644
--- a/tools/perf/util/xyarray.c
+++ b/tools/perf/util/xyarray.c
@@ -12,6 +12,8 @@ struct xyarray *xyarray__new(int xlen, int ylen, size_t entry_size)
 		xy->entry_size = entry_size;
 		xy->row_size   = row_size;
 		xy->entries    = xlen * ylen;
+		xy->max_x      = xlen;
+		xy->max_y      = ylen;
 	}
 
 	return xy;