drm/i915: Update workarounds_emit() to take request structures

Updated the *_ring_workarounds_emit() functions to take requests instead of
ring/context pairs.

For: VIZ-5115
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Tomas Elf <tomas.elf@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>