drm/i915: Kill the undead intel_context.c zombie

It was moved over to gt/ but the backmerge brought it back from the dead.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190528090001.17248-1-chris@chris-wilson.co.uk