test: dm: update test for pins configuration in pinctrl node

Add test for "pins" configuration in gpio uclass with set_state() ops
and test for generic parsing of pinconf_param array).

set_state() is called by:
- pinctrl_generic_set_state
 |- pinctrl_generic_set_state_subnode

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>