drm/i915: Make int __intel_ring_space static

It is only used within intel_ringbuffer.c
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.oc.uk>

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -39,7 +39,7 @@
  */
 #define LEGACY_REQUEST_SIZE 200
 
-int __intel_ring_space(int head, int tail, int size)
+static int __intel_ring_space(int head, int tail, int size)
 {
 	int space = head - tail;
 	if (space <= 0)

drivers/gpu/drm/i915/intel_ringbuffer.h

@@ -523,7 +523,6 @@ intel_ring_offset(struct drm_i915_gem_request *req, void *addr)
 	return offset & (req->ring->size - 1);
 }
 
-int __intel_ring_space(int head, int tail, int size);
 void intel_ring_update_space(struct intel_ring *ring);
 
 void intel_engine_init_global_seqno(struct intel_engine_cs *engine, u32 seqno);