thunderbolt: fix memory leak of object sw

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: b04079837b20 ("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.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>