keystone2: change default boot mode to ubi

To allow out of box demo, change default boot mode to ubi
boot now that NAND is functional in latest EVMs.

Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@ti.com>
Reviewed-by: Tom Rini <trini@ti.com>

include/configs/ks2_evm.h

@@ -245,7 +245,7 @@
 #define CONFIG_BOOTDELAY		3
 #define CONFIG_BOOTFILE			"uImage"
 #define CONFIG_EXTRA_ENV_SETTINGS					\
-	"boot=ramfs\0"							\
+	"boot=ubi\0"							\
 	"tftp_root=/\0"							\
 	"nfs_root=/export\0"						\
 	"mem_lpae=1\0"							\