drm/i915: fix i9xx_crtc_clock_get for multiplied pixels

The dpll actually runs at the port clock so we don't need
to multiply it again with the pixel multiplier to get the
adjusted_mode.clock. This is in contrast to the ironlake
pixel clock readout code which uses the fdi dotclock: That
one does _not_ run with multiplied pixels.

This issue goes back to the original clock readout code added
in

commit f1f644dc
Author: Jesse Barnes <jbarnes@virtuousgeek.org>
Date:   Thu Jun 27 00:39:25 2013 +0300

    drm/i915: get mode clock when reading the pipe config v9

Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -7313,8 +7313,7 @@ static void i9xx_crtc_clock_get(struct intel_crtc *crtc,
 		}
 	}
 
-	pipe_config->adjusted_mode.clock = clock.dot *
-		pipe_config->pixel_multiplier;
+	pipe_config->adjusted_mode.clock = clock.dot;
 }
 
 static void ironlake_crtc_clock_get(struct intel_crtc *crtc,