RDMA/ucma: Fix rdma_ucm_query_ib_service_resp struct padding

RDMA/ucma: Fix rdma_ucm_query_ib_service_resp struct padding

On a few 32-bit architectures, the newly added ib_user_service_rec
structure is not 64-bit aligned the way it is on most regular ones.

Add explicit padding into the rdma_ucm_query_ib_service_resp and
rdma_ucm_resolve_ib_service structures that embed it, so that the layout
is compatible across all of them.

This is an ABI change on i386, aligning it with x86_64 and the other
64-bit architectures to avoid having to use a compat ioctl handler.

Fixes: 810f874eda8e ("RDMA/ucma: Support query resolved service records")
Link: https://patch.msgid.link/r/20251208133311.313977-1-arnd@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>