ssa.c: Updated a couple of comments due to previous commit

commit 42022d33cfcfa3d8a85ad7edf3dcdab746f2ac5d moved
some code from receipt of SSA_MSG_DB_UPDATE message
to SSA_DB_UPDATE_READY message so the comments
relating to flags in message should be updated
accordingly.

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