arm: rmobile: rzg2_beacon: Enable alternative Ethernet PHY

Due to the part shortage, the AR8031 PHY was replaced with a
Micrel KSZ9131. Enabling both config options keeps backward
compatibility with either platform, and both appear to be
auto-detected.

Signed-off-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Marek Vasut <marek.vasut+renesas@gmail.com>
diff --git a/configs/rzg2_beacon_defconfig b/configs/rzg2_beacon_defconfig
index 3678705..b4ea6c6 100644
--- a/configs/rzg2_beacon_defconfig
+++ b/configs/rzg2_beacon_defconfig
@@ -68,6 +68,8 @@
 CONFIG_BITBANGMII=y
 CONFIG_BITBANGMII_MULTI=y
 CONFIG_PHY_ATHEROS=y
+CONFIG_PHY_MICREL=y
+CONFIG_PHY_MICREL_KSZ90X1=y
 CONFIG_RENESAS_RAVB=y
 CONFIG_DM_REGULATOR=y
 CONFIG_DM_REGULATOR_FIXED=y