Currently, if function adds an existing unicast mac address, eventhough
driver will not add this address into hardware, but it will return 0 in
function hclge_add_uc_addr_common(). It will cause the state of this
unicast mac address is ACTIVE in driver, but it should be in TO-ADD state.

To fix this problem, function hclge_add_uc_addr_common() returns -EEXIST
if mac address is existing, and delete two error log to avoid printing
them all the time after this modification.

Fixes: 72110b56 ("net: hns3: return 0 and print warning when hit duplicate MAC")
Signed-off-by: NJian Shen <shenjian15@huawei.com>
Signed-off-by: NGuangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>