net: hns3: Fix potential null pointer defererence of null ae_dev

The reset_prepare and reset_done calls have a null pointer check
on ae_dev however ae_dev is being dereferenced via the call to
ns3_is_phys_func with the ae->pdev argument. Fix this by performing
a null pointer check on ae_dev and hence short-circuiting the
dereference to ae_dev on the call to ns3_is_phys_func.

Addresses-Coverity: ("Dereference before null check")
Fixes: 715c58e9

 ("net: hns3: add suspend and resume pm_ops")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>