rockchip: rk3368: increase SYS_MALLOC_F_LEN to 0x4000

To prevent running out of memory, increase SYS_MALLOC_F_LEN to 0x4000
similar to what rk3399 uses.

Signed-off-by: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/arch/arm/mach-rockchip/rk3368/Kconfig b/arch/arm/mach-rockchip/rk3368/Kconfig
index d6ca5f1..c31915e 100644
--- a/arch/arm/mach-rockchip/rk3368/Kconfig
+++ b/arch/arm/mach-rockchip/rk3368/Kconfig
@@ -49,7 +49,7 @@
 	default "rk3368"
 
 config SYS_MALLOC_F_LEN
-	default 0x2000
+	default 0x4000
 
 config SPL_LIBCOMMON_SUPPORT
 	default y