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/kontron_pitx_imx8m_defconfig b/configs/kontron_pitx_imx8m_defconfig
index e2a87c4..c213347 100644
--- a/configs/kontron_pitx_imx8m_defconfig
+++ b/configs/kontron_pitx_imx8m_defconfig
@@ -83,6 +83,7 @@
 CONFIG_SUPPORT_EMMC_BOOT=y
 CONFIG_FSL_USDHC=y
 CONFIG_PHYLIB=y
+CONFIG_PHY_ANEG_TIMEOUT=20000
 CONFIG_PHY_TI=y
 CONFIG_PHY_GIGE=y
 CONFIG_FEC_MXC=y