ipa: libipa: Add data accessor to Histogram

For debugging purposes it is helpful to access the internal data of the
histogram.  Add an accessor for that.

Signed-off-by: Stefan Klug <stefan.klug@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/ipa/libipa/histogram.cpp

@@ -62,6 +62,12 @@ Histogram::Histogram(Span<const uint32_t> data)
  * \return Number of bins
  */
 
+/**
+ * \fn Histogram::data()
+ * \brief Retrieve the internal data
+ * \return The data
+ */
+
 /**
  * \fn Histogram::total()
  * \brief Retrieve the total number of values in the data set