The CAT875 sub board from Silicon Linux uses Realtek phy and the driver
does not support rxc-skew-ps property.

Fixes: 6b170cd3 ("arm64: dts: renesas: cat875: Add ethernet support")
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lore.kernel.org/r/20201015132350.8360-2-biju.das.jz@bp.renesas.comSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>