drm/drm_dp_mst:remove set but not used variable 'origlen'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/gpu/drm/drm_dp_mst_topology.c:3693:16: warning: variable
‘origlen’ set but not used [-Wunused-but-set-variable]
  int replylen, origlen, curreply;

It looks like never use variable origlen after assign value to it.

Fixes: ad7f8a1f ("drm/helper: add Displayport multi-stream helper (v0.6)")
Signed-off-by: Bo YU <tsu.yubo@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20200118080628.mxcx7bfwdas5m7un@kaowomen.cn

drivers/gpu/drm/drm_dp_mst_topology.c

@@ -3639,7 +3639,7 @@ static bool drm_dp_get_one_sb_msg(struct drm_dp_mst_topology_mgr *mgr, bool up)
 {
 	int len;
 	u8 replyblock[32];
-	int replylen, origlen, curreply;
+	int replylen, curreply;
 	int ret;
 	struct drm_dp_sideband_msg_rx *msg;
 	int basereg = up ? DP_SIDEBAND_MSG_UP_REQ_BASE : DP_SIDEBAND_MSG_DOWN_REP_BASE;
@@ -3659,7 +3659,6 @@ static bool drm_dp_get_one_sb_msg(struct drm_dp_mst_topology_mgr *mgr, bool up)
 	}
 	replylen = msg->curchunk_len + msg->curchunk_hdrlen;
 
-	origlen = replylen;
 	replylen -= len;
 	curreply = len;
 	while (replylen > 0) {