drm/amdgpu/jpeg4.0.3: use num_jpeg_inst for SR-IOV

They should be the same, but use the proper variable.

Reviewed-by: Ruijing Dong <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/amdgpu/jpeg_v4_0_3.c

···
 		if (r)
 			return r;
 
-		for (i = 0; i < adev->vcn.num_vcn_inst; ++i) {
+		for (i = 0; i < adev->jpeg.num_jpeg_inst; ++i) {
 			for (j = 0; j < adev->jpeg.num_jpeg_rings; ++j) {
 				ring = &adev->jpeg.inst[i].ring_dec[j];
 				ring->wptr = 0;