drm/i915: call drm_encoder_init first

Later initialisation of the encoder often requires that
drm_encoder_init() has already been called, for instance, initialiasing
the DDC buses.

Yet another recent regression, as 819f3fb7 depended upon these fixes
which I missed when cherry-picking.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
4 files changed