rockchip: rk3328: use defaule value for SYS_MALLOC_F_LEN

There is no difference in rk3328 board use for SYS_MALLOC_F_LEN,
so we can use default value.

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/arch/arm/mach-rockchip/rk3328/Kconfig b/arch/arm/mach-rockchip/rk3328/Kconfig
index 8ad7f56..a100b95 100644
--- a/arch/arm/mach-rockchip/rk3328/Kconfig
+++ b/arch/arm/mach-rockchip/rk3328/Kconfig
@@ -19,7 +19,7 @@
 	default "rk3328"
 
 config SYS_MALLOC_F_LEN
-	default 0x0800
+	default 0x2000
 
 source "board/rockchip/evb_rk3328/Kconfig"