net: phy: realtek: read actual speed on rtl8211f to detect downshift

net: phy: realtek: read actual speed on rtl8211f to detect downshift

The rtl8211f supports downshift and before commit 5502b218e001
("net: phy: use phy_resolve_aneg_linkmode in genphy_read_status")
the read-back of register MII_CTRL1000 was used to detect the
negotiated link speed.
The code added in commit d445dff2df60 ("net: phy: realtek: read
actual speed to detect downshift") is working fine also for this
phy and it's trivial re-using it to restore the downshift
detection on rtl8211f.

Add the phy specific read_status() pointing to the existing
function rtlgen_read_status().

Signed-off-by: Antonio Borneo <antonio.borneo@st.com>
Link: https://lore.kernel.org/r/478f871a-583d-01f1-9cc5-2eea56d8c2a7@huawei.com
Tested-by: Yonglong Liu <liuyonglong@huawei.com>
Link: https://lore.kernel.org/r/20201124230756.887925-1-antonio.borneo@st.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>