tile: fix missing unlock on error in tile_net_open()

Add the missing unlock before return from function tile_net_open()
in the error handling case.

Introduced by commit f3286a3af89d6db7a488f3e8f02b98d67d50f00c.
(tile: support multiple mPIPE shims in tilegx network driver)

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Acked-by: Chris Metcalf <cmetcalf@tilera.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --cc drivers/net/ethernet/tile/tilegx.c
Simple merge