drm/i915/tv: Fix modeset flickering introduced in 7f58aabc3

The tidy ups in 7f58aabc369014fda3a4a33604ba0a1b63b941ac ("drm/i915:
cleanup per-pipe reg usage") changed intel_crtc->plane to intel_crtc->pipe in
intel_tv_mode_set(). This caused the screen to quickly turn off before
returning whenever modesetting/mode probing took place on my 915GM EeePC
900 creating a flickering effect. This patch changes intel_crtc->pipe back
to intel_crtc->plane which solves the problem for me.

References: https://bugs.freedesktop.org/show_bug.cgi?id=35903
Signed-off-by: Sitsofe Wheeler <sitsofe@yahoo.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Humbly-acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Keith Packard <keithp@keithp.com>

drivers/gpu/drm/i915/intel_tv.c

@@ -1151,10 +1151,10 @@ intel_tv_mode_set(struct drm_encoder *encoder, struct drm_display_mode *mode,
 			    (video_levels->blank << TV_BLANK_LEVEL_SHIFT)));
 	{
 		int pipeconf_reg = PIPECONF(pipe);
-		int dspcntr_reg = DSPCNTR(pipe);
+		int dspcntr_reg = DSPCNTR(intel_crtc->plane);
 		int pipeconf = I915_READ(pipeconf_reg);
 		int dspcntr = I915_READ(dspcntr_reg);
-		int dspbase_reg = DSPADDR(pipe);
+		int dspbase_reg = DSPADDR(intel_crtc->plane);
 		int xpos = 0x0, ypos = 0x0;
 		unsigned int xsize, ysize;
 		/* Pipe must be off here */