net: phy: marvell: fix m88e1111_set_downshift

net: phy: marvell: fix m88e1111_set_downshift

BugLink: https://bugs.launchpad.net/bugs/1929455
[ Upstream commit e7679c55a7249f1315256cfc672d53e84072e223 ]

Changing downshift params without software reset has no effect,
so call genphy_soft_reset() after change downshift params.

As the datasheet says:
Changes to these bits are disruptive to the normal operation therefore,
any changes to these registers must be followed by software reset
to take effect.

Fixes: 5c6bc5199b5d ("net: phy: marvell: add downshift support for M88E1111")
Signed-off-by: Maxim Kochetkov <fido_max@inbox.ru>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>