net: dsa: b53: mmap: add phy ops

stable inclusion
from stable-v5.10.179
commit a36246a7480d9590b9b790a6b5b3ac95f6e41833
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8C809

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a36246a7480d9590b9b790a6b5b3ac95f6e41833



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[ Upstream commit 45977e58 ]

Implement phy_read16() and phy_write16() ops for B53 MMAP to avoid accessing
B53_PORT_MII_PAGE registers which hangs the device.
This access should be done through the MDIO Mux bus controller.

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>
(cherry picked from commit 109b0e14)