drm/i915: Wrap context LRI init in a macro

drm/i915: Wrap context LRI init in a macro

We set up a load of LRIs in the logical ring context. Wrap that stuff
in a macro to avoid typos with position of each reg/value pair in the
context. This also makes it easier to make the register defines type
safe.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1446672017-24497-24-git-send-email-ville.syrjala@linux.intel.com
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>