thunderbolt: fix memory leak of object sw

In the case where the call tb_switch_exceeds_max_depth is true
the error reurn path leaks memory in sw.  Fix this by setting
the return error code to -EADDRNOTAVAIL and returning via the
error exit path err_free_sw_ports to free sw. sw has been kzalloc'd
so the free of the NULL sw->ports is fine.

Addresses-Coverity: ("Resource leak")
Fixes: b0407983 ("thunderbolt: Add initial support for USB4")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Link: https://lore.kernel.org/r/20191220220526.11307-1-colin.king@canonical.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/thunderbolt/switch.c

@@ -1885,8 +1885,10 @@ struct tb_switch *tb_switch_alloc(struct tb *tb, struct device *parent,
 	sw->config.enabled = 0;
 
 	/* Make sure we do not exceed maximum topology limit */
-	if (tb_switch_exceeds_max_depth(sw, depth))
-		return ERR_PTR(-EADDRNOTAVAIL);
+	if (tb_switch_exceeds_max_depth(sw, depth)) {
+		ret = -EADDRNOTAVAIL;
+		goto err_free_sw_ports;
+	}
 
 	/* initialize ports */
 	sw->ports = kcalloc(sw->config.max_port_number + 1, sizeof(*sw->ports),