drm/nouveau: consider CLASS_DISPLAY_3D devices while detecting dsm/optimus

The present code assumes that optimus is present whenever two
VGA (PCI_CLASS_DISPLAY_VGA) devices are present. This does not
seem to be the case of newer laptops with optimus, in which
case the nvidia gpu is a PCI_CLASS_DISPLAY_3D device.

Rework the logic so that we count both VGA and 3D devices,
when contemplating if optimus is present on the platform.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=70208
Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/nouveau/nouveau_acpi.c

@@ -317,6 +317,16 @@ static bool nouveau_dsm_detect(void)
 			has_optimus = 1;
 	}
 
+	while ((pdev = pci_get_class(PCI_CLASS_DISPLAY_3D << 8, pdev)) != NULL) {
+		vga_count++;
+
+		retval = nouveau_dsm_pci_probe(pdev);
+		if (retval & NOUVEAU_DSM_HAS_MUX)
+			has_dsm |= 1;
+		if (retval & NOUVEAU_DSM_HAS_OPT)
+			has_optimus = 1;
+	}
+
 	/* find the optimus DSM or the old v1 DSM */
 	if (has_optimus == 1) {
 		acpi_get_name(nouveau_dsm_priv.dhandle, ACPI_FULL_PATHNAME,