TI DaVinci: DM6446: Fix Compilation error in NAND mode

The Default mode that is built for the Davinci DVEVM happens
to be the NOR mode.
When we want to build for the NAND mode, we get a compilation
error. This is overcome by defining the CONFIG_MTD_DEVICE
flag in the NAND mode.
The image built for NAND mode was successfully tested on the
DaVinci DM6446 EVM.

Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>

include/configs/davinci_dvevm.h

@@ -121,6 +121,7 @@
 #define CONFIG_ENV_SECT_SIZE	512	/* Env sector Size */
 #define CONFIG_ENV_SIZE		(16 << 10)	/* 16 KiB */
 #define CONFIG_MTD_PARTITIONS
+#define CONFIG_MTD_DEVICE
 #define CONFIG_CMD_MTDPARTS
 #define MTDIDS_DEFAULT		\
 	"nand0=davinci_nand.0"