drm/i915: Shuffle sprite register writes into a tighter group

drm/i915: Shuffle sprite register writes into a tighter group

Group the sprite register writes a bit tighter. We want to write
the registers atomically, and so doing the base address/offset
artihmetic within the critical section is pointless when it can
all be done beforehand.

Reviewed-by: Jesse Barnes <[email protected]>
Signed-off-by: Ville Syrjälä <[email protected]>
Signed-off-by: Daniel Vetter <[email protected]>