drm/i915/gt: Expose more parameters for emitting writes into the ring

drm/i915/gt: Expose more parameters for emitting writes into the ring

Add another lower level to emit_ggtt_write so that the GGTT nature of
the write is not hardcoded into the emitter.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201102221057.29626-1-chris@chris-wilson.co.uk
(cherry picked from commit 2739d8cfc50aafff49d599cc0a5bc855445e99a7)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>