ax88796: use generic mdio_bitbang driver

..instead of using hand-crafted and not proper working version.

Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index 65027a7..f4b3927 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -238,8 +238,8 @@
 config AX88796
 	tristate "ASIX AX88796 NE2000 clone support"
 	depends on ARM || MIPS || SUPERH
-	select CRC32
-	select MII
+	select PHYLIB
+	select MDIO_BITBANG
 	help
 	  AX88796 driver, using platform bus to provide
 	  chip detection and resources