drm/nouveau: fix nouveau_dsm_get_client_id()'s return type

The method struct vga_switcheroo_handler::get_client_id() is defined
as returning an 'enum vga_switcheroo_client_id' but the implementation
in this driver, nouveau_dsm_get_client_id(), returns an 'int'.

Fix this by returning 'enum vga_switcheroo_client_id' in this driver too.
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_acpi.c

@@ -193,7 +193,7 @@ static int nouveau_dsm_power_state(enum vga_switcheroo_client_id id,
 	return nouveau_dsm_set_discrete_state(nouveau_dsm_priv.dhandle, state);
 }
 
-static int nouveau_dsm_get_client_id(struct pci_dev *pdev)
+static enum vga_switcheroo_client_id nouveau_dsm_get_client_id(struct pci_dev *pdev)
 {
 	/* easy option one - intel vendor ID means Integrated */
 	if (pdev->vendor == PCI_VENDOR_ID_INTEL)