arm64: defconfig: Enable Renesas RZ/G2L display unit DRM driver

Enable the RZ/G2L display unit DRM drivers used on the RZ/{G2L,G2LC,V2L}
SMARC EVK development boards.
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20240223123646.245655-1-biju.das.jz@bp.renesas.comSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

arch/arm64/configs/defconfig

@@ -854,6 +854,7 @@ CONFIG_DRM_RCAR_DU=m
 CONFIG_DRM_RCAR_DW_HDMI=m
 CONFIG_DRM_RCAR_MIPI_DSI=m
 CONFIG_DRM_RZG2L_MIPI_DSI=m
+CONFIG_DRM_RZG2L_DU=m
 CONFIG_DRM_SUN4I=m
 CONFIG_DRM_SUN6I_DSI=m
 CONFIG_DRM_SUN8I_DW_HDMI=m