drivers: 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: Ia9a4b62c857f7362d67aee4f9de3bb2da1838394
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/58908
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>

src/drivers/uart/oxpcie.c

@@ -12,7 +12,7 @@ static void oxford_oxpcie_enable(struct device *dev)
 {
 	printk(BIOS_DEBUG, "Initializing Oxford OXPCIe952\n");
 
-	struct resource *res = find_resource(dev, PCI_BASE_ADDRESS_0);
+	struct resource *res = probe_resource(dev, PCI_BASE_ADDRESS_0);
 	if (!res) {
 		printk(BIOS_WARNING, "OXPCIe952: No UART resource found.\n");
 		return;