core.c: Don't pass SSA DB object in prepare message in ssa_extract_db_update_prepare

Signed-off-by: Hal Rosenstock <hal@mellanox.com>
ssa.c: In ssa_upstream_initiate_conn, enable keepalives for consumers (ACMs)

Consumer (ACM) nodes need to detect when the other end of the
connection goes away (e.g. SSA app on other end dies, also
doesn't detect a bounced port making it need to reconnect
and maybe rejoin too).

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