drm/i915: Rename intel_context[engine].ringbuf

Perform s/ringbuf/ring/ on the context struct for consistency with the
ring/engine split.

v2: Kill an outdated error_ringbuf label

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469432687-22756-14-git-send-email-chris@chris-wilson.co.uk
Link: http://patchwork.freedesktop.org/patch/msgid/1470174640-18242-3-git-send-email-chris@chris-wilson.co.uk
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 7c42ec4..b67fb4c 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -425,8 +425,8 @@
 	for (n = 0; n < ARRAY_SIZE(ctx->engine); n++) {
 		if (ctx->engine[n].state)
 			per_file_stats(0, ctx->engine[n].state, data);
-		if (ctx->engine[n].ringbuf)
-			per_file_stats(0, ctx->engine[n].ringbuf->obj, data);
+		if (ctx->engine[n].ring)
+			per_file_stats(0, ctx->engine[n].ring->obj, data);
 	}
 
 	return 0;
@@ -2085,8 +2085,8 @@
 			seq_putc(m, ce->initialised ? 'I' : 'i');
 			if (ce->state)
 				describe_obj(m, ce->state);
-			if (ce->ringbuf)
-				describe_ctx_ringbuf(m, ce->ringbuf);
+			if (ce->ring)
+				describe_ctx_ringbuf(m, ce->ring);
 			seq_putc(m, '\n');
 		}