mx6slevk: Remove CONFIG_ETHPRIME option

As mx6slevk has only one Ethernet port, we don't need
to declare CONFIG_ETHPRIME, so just remove it.

Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>

include/configs/mx6slevk.h

@@ -53,7 +53,6 @@
 #define CONFIG_MII
 #define IMX_FEC_BASE			ENET_BASE_ADDR
 #define CONFIG_FEC_XCV_TYPE		RMII
-#define CONFIG_ETHPRIME			"FEC"
 #define CONFIG_FEC_MXC_PHYADDR		0
 
 #define CONFIG_PHYLIB