checks: Add missing phandle_references prereq to interrupts_property

The WARNING macro signature is (name, fn, data, ...prereqs), but
interrupts_property was registered with &phandle_references in the data
slot instead of as a prereq.  Since c->data is const void *, the misuse
compiled silently and the check has been running with num_prereqs == 0.

The bug is normally masked: many other checks (interrupt_map,
gpios_property, omit_unused_nodes, and the *_property checks generated
by WARNING_PROPERTY_PHANDLE_CELLS) correctly list phandle_references as
a prereq, and run_check recurses into prereqs unconditionally.  As long
as any one of them is enabled, fixup_phandle_references is pulled in
transitively and the parser's 0xffffffff placeholder is replaced with
the real phandle before check_interrupts_property reads it.

The bug becomes visible when every other consumer of phandle_references
is silenced (-Eno-phandle_references plus -Wno- for the *_property,
gpios_property and interrupt_map checks).  In that case the placeholder
remains and interrupts_property falsely reports "Invalid phandle" /
"Missing interrupt-parent" on a valid tree.  Reordering check_table[]
could also expose it under default flags.

Add the missing NULL so &phandle_references lands in the prereq slot.

Signed-off-by: Aristo Chen <aristo.chen@canonical.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

checks.c

@@ -1769,7 +1769,7 @@ static void check_interrupts_property(struct check *c,
 			  irq_prop->val.len, (int)(irq_cells * sizeof(cell_t)));
 	}
 }
-WARNING(interrupts_property, check_interrupts_property, &phandle_references);
+WARNING(interrupts_property, check_interrupts_property, NULL, &phandle_references);
 
 static const struct bus_type graph_port_bus = {
 	.name = "graph-port",