drm/nouveau: chan: use channel class definitions

Use channel class definitions instead of magic numbers.
Reviewed-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231002135008.10651-2-dakr@redhat.com

drivers/gpu/drm/nouveau/nouveau_chan.c

@@ -440,9 +440,11 @@ nouveau_channel_init(struct nouveau_channel *chan, u32 vram, u32 gart)
 	}
 
 	/* initialise dma tracking parameters */
-	switch (chan->user.oclass & 0x00ff) {
-	case 0x006b:
-	case 0x006e:
+	switch (chan->user.oclass) {
+	case NV03_CHANNEL_DMA:
+	case NV10_CHANNEL_DMA:
+	case NV17_CHANNEL_DMA:
+	case NV40_CHANNEL_DMA:
 		chan->user_put = 0x40;
 		chan->user_get = 0x44;
 		chan->dma.max = (0x10000 / 4) - 2;