drm/i915: Grab intel_display from the encoder to avoid potential oopsies

In the Linux kernel, the following vulnerability has been resolved: drm/i915: Grab intel_display from the encoder to avoid potential oopsies Grab the intel_display from 'encoder' rather than 'state' in the encoder hooks to avoid the massive footgun that is intel_sanitize_encoder(), which passes NULL as the 'state' argument to encoder .disable() and .post_disable(). TODO: figure out how to actually fix intel_sanitize_encoder()...