soc/intel/common/lpc: Don't open a window for unassigned resources

Don't attempt to open a PMIO window for a resource which doesn't have
the IORESOURCE_ASSIGNED flag set, since there is no point in doing so
and there's a high likelihood that the base address is 0, which will
throw an error.

TEST=build/boot purism/librem_cnl (Mini v2), ensure no errors in cbmem
log for attempting to open a PMIO window for unaassigned resources with
base address 0.

Change-Id: Ifba14a8f134ba12d5f5e9fdbac775d4f82b4c4de
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/80750
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Singer <service+coreboot-gerrit@felixsinger.de>
Reviewed-by: Nico Huber <nico.h@gmx.de>
diff --git a/src/soc/intel/common/block/lpc/lpc.c b/src/soc/intel/common/block/lpc/lpc.c
index b27e09e9..e805035 100644
--- a/src/soc/intel/common/block/lpc/lpc.c
+++ b/src/soc/intel/common/block/lpc/lpc.c
@@ -91,7 +91,7 @@
 		return;
 
 	for (res = dev->resource_list; res; res = res->next) {
-		if (res->flags & IORESOURCE_IO)
+		if ((res->flags & IORESOURCE_IO) && (res->flags & IORESOURCE_ASSIGNED))
 			lpc_open_pmio_window(res->base, res->size);
 	}
 	pch_lpc_set_child_resources(dev);