drm/radeon: remove radeon_ring_index()

Just store the index in the ring structure.
Idea taken from one of Jerome's wip rptr patches.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
index 2d7f06c..be45472 100644
--- a/drivers/gpu/drm/radeon/radeon.h
+++ b/drivers/gpu/drm/radeon/radeon.h
@@ -638,6 +638,7 @@
 	u32			ptr_reg_shift;
 	u32			ptr_reg_mask;
 	u32			nop;
+	u32			idx;
 };
 
 /*
@@ -757,7 +758,6 @@
 void radeon_ib_pool_fini(struct radeon_device *rdev);
 int radeon_ib_ring_tests(struct radeon_device *rdev);
 /* Ring access between begin & end cannot sleep */
-int radeon_ring_index(struct radeon_device *rdev, struct radeon_ring *cp);
 void radeon_ring_free_size(struct radeon_device *rdev, struct radeon_ring *cp);
 int radeon_ring_alloc(struct radeon_device *rdev, struct radeon_ring *cp, unsigned ndw);
 int radeon_ring_lock(struct radeon_device *rdev, struct radeon_ring *cp, unsigned ndw);