rockchip: move SYS_MALLOC_F_LEN to rk3288 own Kconfig

since different rockchip SOC have different size of SRAM,
So the size SYS_MALLOC_F_LEN may different, so move this
config to rk3288 own Kconfig

Signed-off-by: Lin Huang <hl@rock-chips.com>
Acked-by: Simon Glass <sjg@chromium.org>

arch/arm/mach-rockchip/Kconfig

@@ -12,9 +12,6 @@ config ROCKCHIP_RK3288
 config SYS_MALLOC_F
 	default y
 
-config SYS_MALLOC_F_LEN
-	default 0x800
-
 config SPL_DM
 	default y
 

arch/arm/mach-rockchip/rk3288/Kconfig

@@ -19,6 +19,9 @@ config TARGET_CHROMEBOOK_JERRY
 config SYS_SOC
 	default "rockchip"
 
+config SYS_MALLOC_F_LEN
+	default 0x0800
+
 source "board/google/chromebook_jerry/Kconfig"
 
 source "board/firefly/firefly-rk3288/Kconfig"