warp: Select CONFIG_SYS_FSL_ESDHC_HAS_DDR_MODE

Warp has a DDR eMMC, so enable CONFIG_SYS_FSL_ESDHC_HAS_DDR_MODE for better
performance:

reading zImage
5790288 bytes read in 117 ms (47.2 MiB/s)

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Otavio Salvador <otavio@ossystems.com.br>
diff --git a/include/configs/warp.h b/include/configs/warp.h
index e851da0..2eb429e 100644
--- a/include/configs/warp.h
+++ b/include/configs/warp.h
@@ -42,6 +42,7 @@
 #define CONFIG_FSL_USDHC
 #define CONFIG_SYS_FSL_ESDHC_ADDR	0
 #define CONFIG_SYS_FSL_ESDHC_FORCE_VSELECT
+#define CONFIG_SYS_FSL_ESDHC_HAS_DDR_MODE
 
 #define CONFIG_MMC
 #define CONFIG_CMD_MMC