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/n2350_defconfig b/configs/n2350_defconfig
index 5e13d2c..e7d7dea 100644
--- a/configs/n2350_defconfig
+++ b/configs/n2350_defconfig
@@ -75,6 +75,7 @@
 CONFIG_SYS_NAND_ONFI_DETECTION=y
 CONFIG_SPI_FLASH_MACRONIX=y
 CONFIG_SPI_FLASH_STMICRO=y
+CONFIG_PHY_ANEG_TIMEOUT=8000
 CONFIG_PHY_MARVELL=y
 CONFIG_PHY_GIGE=y
 CONFIG_MVNETA=y