ARM: dts: renesas: r9a06g032: Describe GMAC1

ARM: dts: renesas: r9a06g032: Describe GMAC1

The r9a06g032 SoC of the RZ/N1 family features two GMAC devices named
GMAC1/2, that are based on Synopsys cores.  GMAC1 is connected to a
RGMII/RMII converter that is already described in this device tree.

Signed-off-by: Clément Léger <clement.leger@bootlin.com>
[rgantois: commit log]
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Romain Gantois <romain.gantois@bootlin.com>
Link: https://lore.kernel.org/r/20240513-rzn1-gmac1-v7-7-6acf58b5440d@bootlin.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>