net: altera_tse: fix connect_local_phy error path

The connect_local_phy should return NULL (not negative errno) on
error, since its caller expects it.

Signed-off-by: Atsushi Nemoto <atsushi.nemoto@sord.co.jp>
Acked-by: Thor Thayer <thor.thayer@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>