nouveau: initialise has_optimus variable.

We should initialise this to 0 really to avoid getting false positives.

Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/nouveau/nouveau_acpi.c

@@ -270,7 +270,7 @@ static bool nouveau_dsm_detect(void)
 	struct acpi_buffer buffer = {sizeof(acpi_method_name), acpi_method_name};
 	struct pci_dev *pdev = NULL;
 	int has_dsm = 0;
-	int has_optimus;
+	int has_optimus = 0;
 	int vga_count = 0;
 	bool guid_valid;
 	int retval;