rockchip: rk3368: set CONFIG_SYS_BOOTM_LEN to 64MB

Mimicing for example the rk3399, set the SYS_BOOTM_LEN to 64MB so
that regular kernel images can get loaded without problems.

Signed-off-by: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/include/configs/rk3368_common.h b/include/configs/rk3368_common.h
index 86498b4..fbbb8cf 100644
--- a/include/configs/rk3368_common.h
+++ b/include/configs/rk3368_common.h
@@ -31,6 +31,8 @@
 #define CONFIG_SPL_BSS_MAX_SIZE         0x20000
 #define CONFIG_SPL_STACK                0x00188000
 
+#define CONFIG_SYS_BOOTM_LEN	(64 << 20)	/* 64M */
+
 #ifndef CONFIG_SPL_BUILD
 #define ENV_MEM_LAYOUT_SETTINGS \
 	"scriptaddr=0x00500000\0" \