net: dsa: mv88e6xxx: Add stats_get_sset_count|string to ops structure

Different families have different sets of statistics. Abstract this
using a stats_get_sset_count and stats_get_strings op. Each stat has a
bitmap, and the ops implementer uses a bit map mask to count the
statistics which apply for the family, or return the list of strings.
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
v2:
  Rename functions to avoid _ prefix.
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/mv88e6xxx/mv88e6xxx.h

@@ -806,19 +806,21 @@ struct mv88e6xxx_ops {
 	 * are separated out of the STATS_OP register.
 	 */
 	int (*stats_set_histogram)(struct mv88e6xxx_chip *chip);
-};
 
-enum stat_type {
-	BANK0,
-	BANK1,
-	PORT,
+	/* Return the number of strings describing statistics */
+	int (*stats_get_sset_count)(struct mv88e6xxx_chip *chip);
+	void (*stats_get_strings)(struct mv88e6xxx_chip *chip,  uint8_t *data);
 };
 
+#define STATS_TYPE_PORT		BIT(0)
+#define STATS_TYPE_BANK0	BIT(1)
+#define STATS_TYPE_BANK1	BIT(2)
+
 struct mv88e6xxx_hw_stat {
 	char string[ETH_GSTRING_LEN];
 	int sizeof_stat;
 	int reg;
-	enum stat_type type;
+	int type;
 };
 
 static inline bool mv88e6xxx_has(struct mv88e6xxx_chip *chip,