net: airoha: Fix an error handling path in airoha_alloc_gdm_port()

If register_netdev() fails, the error handling path of the probe will not
free the memory allocated by the previous airoha_metadata_dst_alloc() call
because port->dev->reg_state will not be NETREG_REGISTERED.

So, an explicit airoha_metadata_dst_free() call is needed in this case to
avoid a memory leak.

Fixes: af3cf757 ("net: airoha: Move DSA tag in DMA descriptor")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/1b94b91345017429ed653e2f05d25620dc2823f9.1746715755.git.christophe.jaillet@wanadoo.fr


Signed-off-by: Jakub Kicinski <kuba@kernel.org>