Set PHY rxc-skew-ps to 1500 and all other values to their default values.

This is intended to to address failures in the case of 1Gbps communication
using the by h3ulcb board with the KSZ9031RNX phy.
Signed-off-by: Vladimir Barinov <vladimir.barinov@cogentembedded.com>
Signed-off-by: Takeshi Kihara <takeshi.kihara.df@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>