usb: net: migrate USB Ethernet adapters to Kconfig

This migrates ASIX, ASIX88179, MCS7830, RTL8152 and SMSC95XX to Kconfig.
Update defconfigs.

Signed-off-by: Chris Packham <judge.packham@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/smartweb_defconfig b/configs/smartweb_defconfig
index 8e16d9f..accdd5d 100644
--- a/configs/smartweb_defconfig
+++ b/configs/smartweb_defconfig
@@ -51,4 +51,6 @@
 CONFIG_G_DNL_VENDOR_NUM=0x0908
 CONFIG_G_DNL_PRODUCT_NUM=0x02d2
 CONFIG_USB_HOST_ETHER=y
+CONFIG_USB_ETHER_ASIX=y
+CONFIG_USB_ETHER_MCS7830=y
 # CONFIG_EFI_LOADER is not set