net: stmmac: dwmac-sun8i: Support different ranges for TX/RX delay chains

On the R40 SoC, the RX delay chain only has a range of 0~7 (hundred
picoseconds), instead of 0~31. Also the TX delay chain is completely
absent.

This patch adds support for different ranges by adding per-compatible
maximum values in the variant data. A maximum of 0 indicates that the
delay chain is not supported or absent.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>