tests/pm_rpm: Convert to new optparsing

tests/pm_rpm: Convert to new optparsing

Thomas missed the add-hoc parameter parsing in here, which did break
things for Paulo since the core now fails for unknown options.

Convert them over to the new infrastructure, which has the nice upside
that we can remove the comments and put them into the usage available
with --help.

Cc: Thomas Wood <thomas.wood@intel.com>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Tested-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>