core.c: Change name from ssa_extract_handler to core_extract_handler

Signed-off-by: Hal Rosenstock <hal@mellanox.com>
core.c: Add node_type support (so can support combined core + access)

Signed-off-by: Hal Rosenstock <hal@mellanox.com>
plugin/ibssa_opts.cfg: Add node_type

Signed-off-by: Hal Rosenstock <hal@mellanox.com>