drm/i915/guc: general tidying up (submission)

Renaming to more consistent scheme, and updating comments, mostly
about i915_guc_wq_reserve(), aka i915_guc_wq_check_space().

Signed-off-by: Dave Gordon <david.s.gordon@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1473711577-11454-4-git-send-email-david.s.gordon@intel.com
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 16d7cdd..25114336 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -627,7 +627,7 @@
 		 * going any further, as the i915_add_request() call
 		 * later on mustn't fail ...
 		 */
-		ret = i915_guc_wq_check_space(request);
+		ret = i915_guc_wq_reserve(request);
 		if (ret)
 			return ret;
 	}