RDMA/core: Don't make a dummy ib_udata on the stack in create_qp

RDMA/core: Don't make a dummy ib_udata on the stack in create_qp

Sashiko points out the udata for destruction has to be created using
uverbs_get_cleared_udata(). Move it to ib_core_uverbs.c so that the core
qp code can call it. Rework the call chain to pass the struct
uverbs_attr_bundle right up to the driver op callback.

Fixes a possible wild stack reference in drivers during error unwinding,
mlx5 can call rdma_udata_to_drv_context() from destroy_qp() when
destroying a QP.

Fixes: 00a79d6b996d ("RDMA/core: Configure selinux QP during creation")
Link: https://patch.msgid.link/r/1-v1-922fa8e828ba+f7-ib_udata_stack_jgg@nvidia.com
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>