uapi: mptcp: use header file generated from YAML spec

generated with:

 $ ./tools/net/ynl/ynl-gen-c.py --mode uapi \
 > --spec Documentation/netlink/specs/mptcp.yaml \
 > --header -o include/uapi/linux/mptcp_pm.h

Link: https://github.com/multipath-tcp/mptcp_net-next/issues/340


Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: Mat Martineau <martineau@kernel.org>
Link: https://lore.kernel.org/r/20231023-send-net-next-20231023-1-v2-5-16b1f701f900@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>