drm/i915: Remove duplicate golden render state init from execlists

Now that we use the same vfuncs for emitting the batch buffer in both
execlists and legacy, the golden render state initialisation is
identical between both.

v2: gcc wants so.ggtt_offset initialised (even though it is not used)

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469432687-22756-28-git-send-email-chris@chris-wilson.co.uk
Link: http://patchwork.freedesktop.org/patch/msgid/1470174640-18242-19-git-send-email-chris@chris-wilson.co.uk