drm/nv50-nvc0: rename disp->evo to disp->master

More appropriate, and we're about to be using more than just the master
EVO channel.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nv50_display.h

@@ -36,7 +36,7 @@
 #include "nv50_evo.h"
 
 struct nv50_display {
-	struct nouveau_channel *evo;
+	struct nouveau_channel *master;
 	u32 evo_alloc;
 
 	struct {