arm64: dts: allwinner: a100: Add pin definitions for RGMII/RMII

arm64: dts: allwinner: a100: Add pin definitions for RGMII/RMII

The Allwinner A100/A133 supports both RGMII and RMII for its Ethernet
MAC (EMAC) controller. Add corresponding pin definitions.

Note that the sun50iw10 die actually includes two ethernet controllers,
the second of which is rarely exposed to pins. Call the first controller
"emac0" to distinguish it from the second that may be added later.

Signed-off-by: Paul Kocialkowski <paulk@sys-base.io>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Link: https://patch.msgid.link/20250707165155.581579-3-paulk@sys-base.io
Signed-off-by: Chen-Yu Tsai <wens@csie.org>