Currently pointer hwdev is dereferenced when assigning hwif before
hwdev is null checked.  Fix this by only derefencing hwdev after the
null check.

Addresses-Coverity: ("Dereference before null check")
Fixes: 4fdc51bb ("hinic: add support for rss parameters with ethtool")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>