net: mvneta: program 1ms autonegotiation clock divisor

Program the 1ms autonegotiation clock divisor according to the clocking
rate of neta - without this, the 1ms clock ticks at about 660us on
Armada 38x configured for 250MHz. Bring this into correct specification.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Reviewed-by: Marek Behún <kabel@kernel.org>
Link: https://lore.kernel.org/r/E1ms4WD-00EKLK-Ld@rmk-PC.armlinux.org.uk


Signed-off-by: Jakub Kicinski <kuba@kernel.org>