drm/i915: Try harder to complete DP training pattern 1

In commit cdb0e95b
Author: Keith Packard <keithp@keithp.com>
Date:   Tue Nov 1 20:00:06 2011 -0700

    drm/i915: Try harder during dp pattern 1 link training

extra passes were made to retry the same voltage and then retry a full
clock reset. However, as coverity pointed out, we never tried the full
clock reset as we broke out of the loop early.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>