drm/i915: do not warn late about hdmi on port A

The warning should be just a warning. Where it is currently is wrong
since we already registered the connector on drm, meaning it dies later
on a NULL pointer deref if the VBT-overriding we have is removed. Move
the warning up.

Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191108214251.79305-1-lucas.demarchi@intel.com