drm/i915: Leave FDI running after failed link training on LPT-H

Currently we disable some parts of FDI setup after a failed link
training. But despite that we continue with the modeset as if everything
is fine. This results in tons of noise from the state checker, and
it means we're not following the proper modeset sequence for the rest of
crtc enabling, nor for crtc disabling.

Ideally we should abort the modeset and follow the proper disable
sequence to shut off everything we enabled so far, but that would
require a big rework of the modeset code. So instead just leave FDI
up and running in its untrained state, and log an error. This is
what we do on older platforms too.

v2: Fix a typo in the commit message

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1449260570-14670-1-git-send-email-ville.syrjala@linux.intel.com