ARM: uniphier: skip memreserve of unused DRAM bank of LD20

Now the "for" loop here iterates on the detected memory banks.
It must skip unused DRAM banks.

Fixes: c995f3a3c5 ("ARM: uniphier: use gd->bd->bi_dram for memory reserve on LD20 SoC")
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

arch/arm/mach-uniphier/dram_init.c

@@ -256,6 +256,9 @@ int ft_board_setup(void *fdt, bd_t *bd)
 		return 0;
 
 	for (i = 0; i < ARRAY_SIZE(gd->bd->bi_dram); i++) {
+		if (!gd->bd->bi_dram[i].size)
+			continue;
+
 		rsv_addr = gd->bd->bi_dram[i].start + gd->bd->bi_dram[i].size;
 		rsv_addr -= rsv_size;