zhmccli: fix `no_verify` for nested context
zhmccli: fix `no_verify` for nested context

If `is_flag` is set to `True` Click defaults to `False`. Therefore the check

 if no_verify is None:
   no_verify = ctx.obj.no_verify

will always fail. Fix this by setting the default to None for the click option
and apply the actual default later.

Signed-off-by: Marc Hartmayer <7bafc8cd4e6394916d396e4f8cde69753be8d066@linux.ibm.com>

zhmcclient/zhmccli