drm/nouveau/kms/nv50: clean-up encoder functions

Just a shuffle of blocks into an order consistent with the rest of the
code, renaming hdmi/audio funtions for atomic, and removal of unused
code.

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

drivers/gpu/drm/nouveau/nouveau_encoder.h

@@ -59,10 +59,8 @@ struct nouveau_encoder {
 	union {
 		struct {
 			struct nv50_mstm *mstm;
-			u8  dpcd[8];
 			int link_nr;
 			int link_bw;
-			u32 datarate;
 		} dp;
 	};