Revert "drm/i915: Add hot_plug hook for hdmi encoder"

This reverts commit 0b5e88dc.

It completely breaks booting on at least bsw (and maybe more).

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=88081


Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>