arm64: dts: allwinner: a523: Add EMAC0 ethernet MAC

arm64: dts: allwinner: a523: Add EMAC0 ethernet MAC

Add EMAC0 ethernet MAC support which found on A523 variant SoCs,
including the A527/T527 chips. MAC0 is compatible to the A64 chip which
requires an external PHY. This patch only add RGMII pins for now.

Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Corentin LABBE <clabbe.montjoie@gmail.com>
Signed-off-by: Yixun Lan <dlan@gentoo.org>
Link: https://patch.msgid.link/20250430-01-sun55i-emac0-v3-3-6fc000bbccbd@gentoo.org
Signed-off-by: Chen-Yu Tsai <wens@csie.org>