net: atlantic: make hw_get_regs optional

This patch fixes potential crash in case if hw_get_regs is NULL.
Signed-off-by: Mark Starovoytov <mstarovoitov@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/aquantia/atlantic/aq_nic.c

@@ -778,6 +778,9 @@ int aq_nic_get_regs(struct aq_nic_s *self, struct ethtool_regs *regs, void *p)
 	u32 *regs_buff = p;
 	int err = 0;
 
+	if (unlikely(!self->aq_hw_ops->hw_get_regs))
+		return -EOPNOTSUPP;
+
 	regs->version = 1;
 
 	err = self->aq_hw_ops->hw_get_regs(self->aq_hw,
@@ -792,6 +795,9 @@ int aq_nic_get_regs(struct aq_nic_s *self, struct ethtool_regs *regs, void *p)
 
 int aq_nic_get_regs_count(struct aq_nic_s *self)
 {
+	if (unlikely(!self->aq_hw_ops->hw_get_regs))
+		return 0;
+
 	return self->aq_nic_cfg.aq_hw_caps->mac_regs_count;
 }