ksgen/docstring: remove unnecessary import Mapping

Change-Id: Ic7c2e8b6898e94d1e72abbcc035217a951a0fa06
ksgen/docstring: fix crash when --config-dir=.

Fixes the crash when ksgen is passed the  config dir '.'. Fixed
by sanitizing the input path.

Change-Id: I811e28c92b5d9dd3c392297a112dacfab3e75918