hsi: Fix build regression due to netdev destructor fix.

> ../drivers/hsi/clients/ssi_protocol.c:1069:5: error: 'struct net_device' has no member named 'destructor'

Reported-by: Mark Brown <broonie@kernel.org>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>