drm/i915/icl: unconditionally init DDI for every port

On ICP, port present straps (from SFUSE_STRAP PCH register) are no
longer supported. Software should determine the presence through BIOS
VBT, hotplug or other mechanisms.

v2: Improve commit message (Lucas).

Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180522002558.29262-14-paulo.r.zanoni@intel.com