drm/i915: Make IS_GEN macros only take dev_priv

Saves 1416 bytes of .rodata strings.

v2: Add parantheses around dev_priv. (Ville Syrjala)

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: David Weinehall <david.weinehall@linux.intel.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Jani Nikula <jani.nikula@linux.intel.com>
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1476352990-2504-1-git-send-email-tvrtko.ursulin@linux.intel.com
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index b20c1cc..515c206 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -4558,7 +4558,7 @@
 	else if (IS_VALLEYVIEW(dev_priv))
 		num_levels = 1;
 	else
-		num_levels = ilk_wm_max_level(dev) + 1;
+		num_levels = ilk_wm_max_level(dev_priv) + 1;
 
 	drm_modeset_lock_all(dev);
 
@@ -4674,7 +4674,7 @@
 	else if (IS_VALLEYVIEW(dev_priv))
 		num_levels = 1;
 	else
-		num_levels = ilk_wm_max_level(dev) + 1;
+		num_levels = ilk_wm_max_level(dev_priv) + 1;
 
 	if (len >= sizeof(tmp))
 		return -EINVAL;