sfc: fix potential memory leak in efx_mae_process_mport()

In efx_mae_enumerate_mports(), memory allocated for mae_mport_desc is
passed as a argument to efx_mae_process_mport(), but when the error path
in efx_mae_process_mport() gets executed, the memory allocated for desc
gets leaked.

Fix that by freeing the memory allocation before returning error.

Fixes: a6a15ac ("sfc: enumerate mports in ef100")
Acked-by: Edward Cree <ecree.xilinx@gmail.com>
Signed-off-by: Abdun Nihaal <nihaal@cse.iitm.ac.in>
Link: https://patch.msgid.link/20251023141844.25847-1-nihaal@cse.iitm.ac.in
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: Abdun Nihaal

drivers/net/ethernet/sfc/mae.c

@@ -1090,6 +1090,9 @@ void efx_mae_remove_mport(void *desc, void *arg)
 	kfree(mport);
 }
 
+/*
+ * Takes ownership of @desc, even if it returns an error
+ */
 static int efx_mae_process_mport(struct efx_nic *efx,
 				 struct mae_mport_desc *desc)
 {
@@ -1100,6 +1103,7 @@ static int efx_mae_process_mport(struct efx_nic *efx,
 	if (!IS_ERR_OR_NULL(mport)) {
 		netif_err(efx, drv, efx->net_dev,
 			  "mport with id %u does exist!!!\n", desc->mport_id);
+		kfree(desc);
 		return -EEXIST;
 	}