mx53ard: Remove unused CONFIG_MII_GASKET

CONFIG_MII_GASKET is not defined anywhere, so remove it.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
diff --git a/include/configs/mx53ard.h b/include/configs/mx53ard.h
index f4512ff..8da381f 100644
--- a/include/configs/mx53ard.h
+++ b/include/configs/mx53ard.h
@@ -68,7 +68,6 @@
 /* Eth Configs */
 #define CONFIG_HAS_ETH1
 #define CONFIG_MII
-#define CONFIG_MII_GASKET
 #define CONFIG_DISCOVER_PHY
 
 #define CONFIG_CMD_PING