dm: pci: Check board information pointer in decode_regions()

PCI enumeration may happen very early on an x86 board. The board
information pointer should have been checked in decode_regions()
as its space may not be allocated yet.

With this commit, Intel Galileo board boots again.

Fixes: 664758c ("pci: Fix decode regions for memory banks")
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

drivers/pci/pci-uclass.c

@@ -876,6 +876,9 @@ static int decode_regions(struct pci_controller *hose, ofnode parent_node,
 #ifdef CONFIG_NR_DRAM_BANKS
 	bd_t *bd = gd->bd;
 
+	if (!bd)
+		return 0;
+
 	for (i = 0; i < CONFIG_NR_DRAM_BANKS; ++i) {
 		if (bd->bi_dram[i].size) {
 			pci_set_region(hose->regions + hose->region_count++,