powerpc/powernv/npu-dma.c: Fix opal_npu_destroy_context() call

powerpc/powernv/npu-dma.c: Fix opal_npu_destroy_context() call

BugLink: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1692580
opal_npu_destroy_context() should be called with the NPU PHB, not the
PCIe PHB.

Fixes: 1ab66d1fbada ("powerpc/powernv: Introduce address translation services for Nvlink2")
Signed-off-by: Alistair Popple <alistair@popple.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
(cherry picked from commit 415ba3c157b9de7edc59468d19d48c1d15972a75)
Signed-off-by: Breno Leitao <breno.leitao@gmail.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>