After changing rhashtable_walk_start to return void, start_fail would
never be set other value than 0, and the checking for start_fail is
pointless, so remove it.

Fixes: 97a6ec4a ("rhashtable: Change rhashtable_walk_start to return void")
Signed-off-by: NXin Long <lucien.xin@gmail.com>
Acked-by: NNeil Horman <nhorman@tuxdriver.com>
Acked-by: NMarcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>