net: hsr: create an API to get hsr port type

net: hsr: create an API to get hsr port type

Since the introduction of HSR_PT_INTERLINK in commit 5055cccfc2d1 ("net:
hsr: Provide RedBox support (HSR-SAN)"), we see that different port
types require different settings for hardware offload, which was not the
case before when we only had HSR_PT_SLAVE_A and HSR_PT_SLAVE_B. But
there is currently no way to know which port is which type, so create
the hsr_get_port_type() API function and export it.

When hsr_get_port_type() is called from the device driver, the port can
must be found in the HSR port list. An important use case is for this
function to work from offloading drivers' NETDEV_CHANGEUPPER handler,
which is triggered by hsr_portdev_setup() -> netdev_master_upper_dev_link().
Therefore, we need to move the addition of the hsr_port to the HSR port
list prior to calling hsr_portdev_setup(). This makes the error
restoration path also more similar to hsr_del_port(), where
kfree_rcu(port) is already used.

Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Lukasz Majewski <lukma@denx.de>
Signed-off-by: Xiaoliang Yang <xiaoliang.yang_1@nxp.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Łukasz Majewski <lukma@nabladev.com>
Link: https://patch.msgid.link/20251130131657.65080-3-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>