rockchip: rk3288: use default value for SYS_MALLOC_F_LEN

There is no difference in rk3288 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/rk3288/Kconfig b/arch/arm/mach-rockchip/rk3288/Kconfig
index a03b36b..9a4c130 100644
--- a/arch/arm/mach-rockchip/rk3288/Kconfig
+++ b/arch/arm/mach-rockchip/rk3288/Kconfig
@@ -146,7 +146,7 @@
 	default "rk3288"
 
 config SYS_MALLOC_F_LEN
-	default 0x0800
+	default 0x2000
 
 config SPL_DRIVERS_MISC_SUPPORT
 	default y