ethtool: dsa: add pretty dump

This patch adds the preliminary bits for pretty dumping the registers
of the "dsa" kernel drivers.

This patch does not pretty dump anything yet.

Following patches will add support for the "mv88e6xxx" DSA driver.

Signed-off-by: Vivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/internal.h b/internal.h
index b239dc7..84b0f9c 100644
--- a/internal.h
+++ b/internal.h
@@ -354,4 +354,7 @@
 /* MICROCHIP LAN78XX USB ETHERNET Controller */
 int lan78xx_dump_regs(struct ethtool_drvinfo *info, struct ethtool_regs *regs);
 
+/* Distributed Switch Architecture */
+int dsa_dump_regs(struct ethtool_drvinfo *info, struct ethtool_regs *regs);
+
 #endif /* ETHTOOL_INTERNAL_H__ */