net: phy: Replace PHY_ANEG_TIMEOUT with Kconfig symbol

Switch PHY_ANEG_TIMEOUT to CONFIG_PHY_ANEG_TIMEOUT Kconfig symbol.
This removes one more configuration headers option finalizes its
Kconfig symbol conversion. No functional change expected.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
diff --git a/configs/imx8mp_rsb3720a1_6G_defconfig b/configs/imx8mp_rsb3720a1_6G_defconfig
index 6dd51a3..4b0b71d 100644
--- a/configs/imx8mp_rsb3720a1_6G_defconfig
+++ b/configs/imx8mp_rsb3720a1_6G_defconfig
@@ -127,6 +127,7 @@
 CONFIG_SPI_FLASH_BAR=y
 CONFIG_SPI_FLASH_STMICRO=y
 CONFIG_SPI_FLASH_WINBOND=y
+CONFIG_PHY_ANEG_TIMEOUT=20000
 CONFIG_PHY_REALTEK=y
 CONFIG_DM_ETH_PHY=y
 CONFIG_PHY_GIGE=y