net: phy: mscc-miim: reject clause 45 register accesses

net: phy: mscc-miim: reject clause 45 register accesses

BugLink: https://bugs.launchpad.net/bugs/1969107
[ Upstream commit 8d90991e5bf7fdb9f264f5f579d18969913054b7 ]

The driver doesn't support clause 45 register access yet, but doesn't
check if the access is a c45 one either. This leads to spurious register
reads and writes. Add the check.

Fixes: 542671fe4d86 ("net: phy: mscc-miim: Add MDIO driver")
Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
(cherry picked from commit fb45e80b2194ee6f615dfde4ab86da4144811126)
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>