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/cgtqmx6eval_defconfig b/configs/cgtqmx6eval_defconfig
index 7a24a2c..fc33610 100644
--- a/configs/cgtqmx6eval_defconfig
+++ b/configs/cgtqmx6eval_defconfig
@@ -63,5 +63,6 @@
 CONFIG_G_DNL_VENDOR_NUM=0x0525
 CONFIG_G_DNL_PRODUCT_NUM=0xa4a5
 CONFIG_USB_HOST_ETHER=y
+CONFIG_USB_ETHER_ASIX=y
 # CONFIG_VIDEO_SW_CURSOR is not set
 CONFIG_OF_LIBFDT=y