powerpc/powernv/npu: Prevent overwriting of pnv_npu2_init_contex() callback parameters
There is a single npu context per set of callback parameters. Callers
should be prevented from overwriting existing callback values so
instead return an error if different parameters are passed.
Fixes: 1ab66d1fbada ("powerpc/powernv: Introduce address translation services for Nvlink2") Cc: stable@vger.kernel.org # v4.12+ Signed-off-by: Alistair Popple <alistair@popple.id.au> Reviewed-by: Mark Hairgrove <mhairgrove@nvidia.com> Tested-by: Mark Hairgrove <mhairgrove@nvidia.com> Reviewed-by: Balbir Singh <bsingharora@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>