asix: AX88172A driver depends on phylib

Since commit 16626b0cc3d5afe250850f96759b241f8a403b52 the asix
driver depends on the phylib. Select phylib when the asix driver is
selected.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Cc: kernel-janitors@vger.kernel.org
Signed-off-by: Christian Riesch <christian.riesch@omicron.at>
Tested-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/usb/Kconfig b/drivers/net/usb/Kconfig
index 833e32f..c1ae769 100644
--- a/drivers/net/usb/Kconfig
+++ b/drivers/net/usb/Kconfig
@@ -134,6 +134,7 @@
 	tristate "ASIX AX88xxx Based USB 2.0 Ethernet Adapters"
 	depends on USB_USBNET
 	select CRC32
+	select PHYLIB
 	default y
 	help
 	  This option adds support for ASIX AX88xxx based USB 2.0