Pull in upstream commit:

Author: Ville Syrj辰l辰 <ville.syrjala@linux.intel.com>
Date:  Mon Jun 9 16:20:46 2014 +0300

    drm/i915: Avoid div-by-zero when pixel_multiplier is zero

On certain platforms pixel_multiplier is read out in
.get_pipe_config(), but it also gets used to calculate the
pixel clock in intel_sdvo_get_config(). If the pipe is disabled
but some SDVO outputs are active, we may end up dividing by zero
in intel_sdvo_get_config().

Fixes https://bugs.freedesktop.org/show_bug.cgi?id=76520

(maya)