net: dsa: mv88e6xxx: Fix u64 statistics

BugLink: https://bugs.launchpad.net/bugs/1822271

[ Upstream commit 6e46e2d8 ]

The switch maintains u64 counters for the number of octets sent and
received. These are kept as two u32's which need to be combined.  Fix
the combing, which wrongly worked on u16's.

Fixes: 80c4627b ("dsa: mv88x6xxx: Refactor getting a single statistic")
Reported-by: Chris Healy <Chris.Healy@zii.aero>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Juerg Haefliger <juerg.haefliger@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/net/dsa/mv88e6xxx.c

@@ -712,7 +712,7 @@ static uint64_t _mv88e6xxx_get_ethtool_stat(struct dsa_switch *ds,
 		if (s->sizeof_stat == 8)
 			_mv88e6xxx_stats_read(ds, s->reg + 1, &high);
 	}
-	value = (((u64)high) << 16) | low;
+	value = (((u64)high) << 32) | low;
 	return value;
 }