checks: Ensure '#interrupt-cells' only exists in interrupt providers

The interrupt provider check currently checks if an interrupt provider
has #interrupt-cells, but not whether #interrupt-cells is present
outside of interrupt-providers. Rework the check to cover the latter
case.

Cc: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Rob Herring <robh@kernel.org>
Message-Id: <20211011191245.1009682-4-robh@kernel.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

checks.c

@@ -1573,14 +1573,20 @@ static void check_interrupt_provider(struct check *c,
 				     struct node *node)
 {
 	struct property *prop;
+	bool irq_provider = node_is_interrupt_provider(node);
 
-	if (!node_is_interrupt_provider(node))
+	prop = get_property(node, "#interrupt-cells");
+	if (irq_provider && !prop) {
+		FAIL(c, dti, node,
+		     "Missing '#interrupt-cells' in interrupt provider");
 		return;
+	}
 
-	prop = get_property(node, "#interrupt-cells");
-	if (!prop)
+	if (!irq_provider && prop) {
 		FAIL(c, dti, node,
-		     "Missing #interrupt-cells in interrupt provider");
+		     "'#interrupt-cells' found, but node is not an interrupt provider");
+		return;
+	}
 }
 WARNING(interrupt_provider, check_interrupt_provider, NULL, &interrupts_extended_is_cell);