drm/amd/amdgpu: Correct ring wptr address in debugfs (v2)

On gfx9 hardware the value is not wrapped and is a 64-bit value.  So
we reduce it modulo the ring size.
Signed-off-by: Tom St Denis <tom.stdenis@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>

(v2) use buf_mask instead of computing on the fly
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c

@@ -320,8 +320,8 @@ static ssize_t amdgpu_debugfs_ring_read(struct file *f, char __user *buf,
 
 	if (*pos < 12) {
 		early[0] = amdgpu_ring_get_rptr(ring);
-		early[1] = amdgpu_ring_get_wptr(ring);
-		early[2] = ring->wptr;
+		early[1] = amdgpu_ring_get_wptr(ring) & ring->buf_mask;
+		early[2] = ring->wptr & ring->buf_mask;
 		for (i = *pos / 4; i < 3 && size; i++) {
 			r = put_user(early[i], (uint32_t *)buf);
 			if (r)