python: netcmd: SUPPRESS_HELP constant has no effect here

python: netcmd: SUPPRESS_HELP constant has no effect here

Where it is used, on a few options, the constant should be used
directly instead.

This means that in the following commit, the Option subclass of
SambaOption can be removed, as it will become redundant.

Signed-off-by: Rob van der Linde <rob@catalyst.net.nz>
Reviewed-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>