dt-bindings: net: sun8i-emac: Rename A523 EMAC0 to GMAC0

dt-bindings: net: sun8i-emac: Rename A523 EMAC0 to GMAC0

The datasheets refer to the first Ethernet controller as GMAC0, not
EMAC0.

Rename the compatible string to align with the datasheets. A fix for
the device trees will be sent separately.

Fixes: 0454b9057e98 ("dt-bindings: net: sun8i-emac: Add A523 EMAC0 compatible")
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://patch.msgid.link/20250628054438.2864220-2-wens@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>