[PATCH-for-5.2 v2] acpi-build: Fix maybe-uninitialized warning when ACPI hotplug is off

[Ani Sinha]

 This fixes the following warning (gcc 9.3.0 on Ubuntu):

  ../hw/i386/acpi-build.c: In function 'build_append_pci_bus_devices':
  ../hw/i386/acpi-build.c:496:9: error: 'method' may be used uninitialized
  in this function [-Werror=maybe-uninitialized]
    496 |         aml_append(parent_scope, method);
        |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  cc1: all warnings being treated as errors

Fixes: df4008c9c59 ("piix4: don't reserve hw resources when hotplug is off 
globally")
Reported-by: Philippe Mathieu-Daudé <phi...@redhat.com>
Signed-off-by: Ani Sinha <a...@anisinha.ca>
---
 hw/i386/acpi-build.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index 4f66642d88..431f5ba247 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -349,7 +349,7 @@ static void build_append_pcihp_notify_entry(Aml *method, 
int slot)
 static void build_append_pci_bus_devices(Aml *parent_scope, PCIBus *bus,
                                          bool pcihp_bridge_en)
 {
-    Aml *dev, *notify_method = NULL, *method;
+    Aml *dev, *notify_method = NULL, *method = NULL;
     QObject *bsel;
     PCIBus *sec;
     int i;
@@ -463,6 +463,7 @@ static void build_append_pci_bus_devices(Aml *parent_scope, 
PCIBus *bus,
      * Add this method for root bus only when hotplug is enabled since DSDT
      * expects it.
      */
+    method = NULL;
     if (bsel || pcihp_bridge_en) {
         method = aml_method("PCNT", 0, AML_NOTSERIALIZED);
     }
@@ -492,7 +493,7 @@ static void build_append_pci_bus_devices(Aml *parent_scope, 
PCIBus *bus,
         }
     }
 
-    if (bsel || pcihp_bridge_en) {
+    if (method) {
         aml_append(parent_scope, method);
     }
     qobject_unref(bsel);
-- 
2.25.1