We don't want to preserve the DDI A 4 lane bit on ICL.

Fixes: 3d2011cf ("drm/i915/icl: remove port A/E lane sharing limitation.")
Cc: Mahesh Kumar <mahesh1.kumar@intel.com>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180306104155.3526-1-jani.nikula@intel.com