nb/intel: Replace bad uses of find_resource

The `find_resource` function will never return null (will die instead).
In cases where the existing code already accounts for null pointers, it
is better to use `probe_resource` instead, which returns a null pointer
instead of dying.

Change-Id: I617fea8a09049e9a87130640835ea6c3e2faec60
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/58906
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Werner Zeh <werner.zeh@siemens.com>

src/northbridge/intel/sandybridge/gma.c

@@ -308,7 +308,7 @@ static void gma_pm_init_pre_vbios(struct device *dev)
 
 	printk(BIOS_DEBUG, "GT Power Management Init\n");
 
-	gtt_res = find_resource(dev, PCI_BASE_ADDRESS_0);
+	gtt_res = probe_resource(dev, PCI_BASE_ADDRESS_0);
 	if (!gtt_res || !gtt_res->base)
 		return;