boards: tam3517-common: enable gpmc prefetch mode

Since the tam3517 base board has a 16bit wide nand connected to
the gpmc, enable the prefetch mode, since that is now supported.

Cc: Scott Wood <scottwood@freescale.com>
Cc: Tom Rini <trini@konsulko.com>
Cc: pekon gupta <pekon@ti.com>
Cc: Nishanth Menon <nm@ti.com>
Cc: Daniel Mack <zonque@gmail.com>
Cc: Tapani Utriainen <tapani@technexion.com>

Signed-off-by: Jeroen Hofstee <jeroen@myspectrum.nl>
Reviewed-by: Tom Rini <trini@konsulko.com>

include/configs/tam3517-common.h

@@ -260,6 +260,7 @@
 #define CONFIG_SYS_NAND_ECCSIZE		256
 #define CONFIG_SYS_NAND_ECCBYTES	3
 #define CONFIG_NAND_OMAP_ECCSCHEME	OMAP_ECC_HAM1_CODE_SW
+#define CONFIG_NAND_OMAP_GPMC_PREFETCH
 
 #define CONFIG_SYS_NAND_U_BOOT_START	CONFIG_SYS_TEXT_BASE