warp: Adjust CONFIG_SYS_DFU_DATA_BUF_SIZE

Adjust CONFIG_SYS_DFU_DATA_BUF_SIZE in order to avoid the following error
when running the dfu command:
=> dfu 0 mmc 0
dfu_get_buf: Could not memalign 0x2000000 bytes

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
diff --git a/include/configs/warp.h b/include/configs/warp.h
index 2673948..f0a912b 100644
--- a/include/configs/warp.h
+++ b/include/configs/warp.h
@@ -94,7 +94,7 @@
 #define CONFIG_CMD_DFU
 #define CONFIG_DFU_FUNCTION
 #define CONFIG_DFU_MMC
-#define CONFIG_SYS_DFU_DATA_BUF_SIZE SZ_32M
+#define CONFIG_SYS_DFU_DATA_BUF_SIZE SZ_16M
 #define DFU_DEFAULT_POLL_TIMEOUT 300
 
 #define CONFIG_EXTRA_ENV_SETTINGS \