ssa.c: A couple of cosmetic commentary changes

Also, a couple of cosmetic formatting changes to add a blank line

Signed-off-by: Hal Rosenstock <hal@mellanox.com>
ssa.c: Only SSA Set method is unsolicited currently in ssa_open_port

Removed unneeded unsolicited methods from being registered with umad

Signed-off-by: Hal Rosenstock <hal@mellanox.com>
ssa.c: Indicate ssa_open_port failures and handle such failures in ssa_open_dev

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