drm/i915: HDMI/DP - ELD info refresh support for Haswell

ELD info should be updated dynamically according to hot plug event.
For haswell chip, clear/set the eld valid bit and output enable bit
from callback intel_disable/eanble_ddi().

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Signed-off-by: Wang Xingchao <xingchao.wang@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>