drm/nouveau/bios: improve error handling when reading the vbios from ACPI

Reported-by: Pawel Sikora <pawel.sikora@agmk.net>
Signed-off-by: Martin Peres <martin.peres@labri.fr>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/core/subdev/bios/base.c

@@ -188,8 +188,10 @@ nouveau_bios_shadow_acpi(struct nouveau_bios *bios)
 	int ret, cnt, i;
 	u8  data[3];
 
-	if (!nouveau_acpi_rom_supported(pdev))
+	if (!nouveau_acpi_rom_supported(pdev)) {
+		bios->data = NULL;
 		return;
+	}
 
 	bios->size = 0;
 	if (nouveau_acpi_get_bios_chunk(data, 0, 3) == 3)