arm64: dts: allwinner: a100: Add EMAC support

arm64: dts: allwinner: a100: Add EMAC support

The Allwinner A100/A133 Ethernet MAC (EMAC) is compatible with the A64
one and needs access to the syscon register for control of the
top-level integration of the unit.

Note that there are two such controllers on the sun50iw10 die, which are
the same unit with a different top-level syscon register offset.

Signed-off-by: Paul Kocialkowski <paulk@sys-base.io>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Link: https://patch.msgid.link/20250707165155.581579-4-paulk@sys-base.io
Signed-off-by: Chen-Yu Tsai <wens@csie.org>