net: hns3: return error code when function fails

net: hns3: return error code when function fails

Currently, in hclge_mii_ioctl(), the operation to
read the PHY register (SIOCGMIIREG) always returns 0.

This patch changes the return type of hclge_read_phy_reg(),
returning an error code when the function fails.

Fixes: 024712f51e57 ("net: hns3: add ioctl support for imp-controlled PHYs")
Signed-off-by: Jijie Shao <shaojijie@huawei.com>
Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Link: https://patch.msgid.link/20251023131338.2642520-2-shaojijie@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>