pci: Make load_oprom and run_oprom independent

At present should_load_oprom() calls board_should_run_oprom() to
determine whether oprom should be loaded. But sometimes we just
want to load oprom without running. Make them independent.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/pci/pci_rom.c b/drivers/pci/pci_rom.c
index 3ae9231..a168559 100644
--- a/drivers/pci/pci_rom.c
+++ b/drivers/pci/pci_rom.c
@@ -41,10 +41,7 @@
 
 static bool should_load_oprom(struct udevice *dev)
 {
-	if (board_should_run_oprom(dev))
-		return 1;
-
-	return 0;
+	return true;
 }
 
 __weak uint32_t board_map_oprom_vendev(uint32_t vendev)