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/sbc8641d_defconfig b/configs/sbc8641d_defconfig
index 715773f..5524685 100644
--- a/configs/sbc8641d_defconfig
+++ b/configs/sbc8641d_defconfig
@@ -16,6 +16,7 @@
 CONFIG_DOS_PARTITION=y
 # CONFIG_MMC is not set
 CONFIG_MTD_NOR_FLASH=y
-CONFIG_PHYLIB=y
+CONFIG_NETDEVICES=y
+CONFIG_TSEC_ENET=y
 CONFIG_SYS_NS16550=y
 CONFIG_OF_LIBFDT=y