drm/i915: switch ring->id to be a real id

... and add a helpr function for the places where we want a flag.

This way we can use ring->id to index into arrays.

v2: Resurrect the missing beautification-space Chris Wilson noted.
I'm moving this space around because I'll reuse ring_str in the next
patch.

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 68281c9..c8b9cc0 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -1,13 +1,6 @@
 #ifndef _INTEL_RINGBUFFER_H_
 #define _INTEL_RINGBUFFER_H_
 
-enum {
-	RCS = 0x0,
-	VCS,
-	BCS,
-	I915_NUM_RINGS,
-};
-
 struct  intel_hw_status_page {
 	u32	__iomem	*page_addr;
 	unsigned int	gfx_addr;
@@ -36,10 +29,11 @@
 struct  intel_ring_buffer {
 	const char	*name;
 	enum intel_ring_id {
-		RING_RENDER = 0x1,
-		RING_BSD = 0x2,
-		RING_BLT = 0x4,
+		RCS = 0x0,
+		VCS,
+		BCS,
 	} id;
+#define I915_NUM_RINGS 3
 	u32		mmio_base;
 	void		__iomem *virtual_start;
 	struct		drm_device *dev;
@@ -119,6 +113,12 @@
 	void *private;
 };
 
+static inline unsigned
+intel_ring_flag(struct intel_ring_buffer *ring)
+{
+	return 1 << ring->id;
+}
+
 static inline u32
 intel_ring_sync_index(struct intel_ring_buffer *ring,
 		      struct intel_ring_buffer *other)