net: dsa: mv88e6xxx: fix speed setting for CPU/DSA ports

Commit 3c783b8 ("net: dsa: mv88e6xxx: get rid of SPEED_MAX setting")
stopped relying on SPEED_MAX constant and hardcoded speed settings
for the switch ports and rely on phylink configuration.

It turned out, however, that when the relevant code is called,
the mac_capabilites of CPU/DSA port remain unset.
mv88e6xxx_setup_port() is called via mv88e6xxx_setup() in
dsa_tree_setup_switches(), which precedes setting the caps in
phylink_get_caps down in the chain of dsa_tree_setup_ports().

As a result the mac_capabilites are 0 and the default speed for CPU/DSA
port is 10M at the start. To fix that, execute mv88e6xxx_get_caps()
and obtain the capabilities driectly.

Fixes: 3c783b8 ("net: dsa: mv88e6xxx: get rid of SPEED_MAX setting")
Signed-off-by: Marcin Wojtas <mw@semihalf.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Link: https://lore.kernel.org/r/20220726230918.2772378-1-mw@semihalf.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: wojtas-marcin

drivers/net/dsa/mv88e6xxx/chip.c

@@ -3293,7 +3293,12 @@ static int mv88e6xxx_setup_port(struct mv88e6xxx_chip *chip, int port)
 	 * port and all DSA ports to their maximum bandwidth and full duplex.
 	 */
 	if (dsa_is_cpu_port(ds, port) || dsa_is_dsa_port(ds, port)) {
-		unsigned long caps = dp->pl_config.mac_capabilities;
+		struct phylink_config pl_config = {};
+		unsigned long caps;
+
+		mv88e6xxx_get_caps(ds, port, &pl_config);
+
+		caps = pl_config.mac_capabilities;
 
 		if (chip->info->ops->port_max_speed_mode)
 			mode = chip->info->ops->port_max_speed_mode(port);