treewide: Migrate CONFIG_TSEC_ENET to Kconfig

Migrate the CONFIG_TSEC_ENET option to Kconfig.

Signed-off-by: Mario Six <mario.six@gdsys.cc>
diff --git a/configs/MPC8572DS_36BIT_defconfig b/configs/MPC8572DS_36BIT_defconfig
index 36a0728..2967428 100644
--- a/configs/MPC8572DS_36BIT_defconfig
+++ b/configs/MPC8572DS_36BIT_defconfig
@@ -24,10 +24,10 @@
 CONFIG_SYS_FSL_DDR2=y
 # CONFIG_MMC is not set
 CONFIG_MTD_NOR_FLASH=y
-CONFIG_PHYLIB=y
 CONFIG_NETDEVICES=y
 CONFIG_PHY_GIGE=y
 CONFIG_E1000=y
+CONFIG_TSEC_ENET=y
 CONFIG_SYS_NS16550=y
 CONFIG_USB=y
 CONFIG_USB_EHCI_PCI=y