pinctrl: stm32: add information on pin configuration

Add information on pin configuration used for pinmux command:
- bias configuration for output (disable, pull up, pull down)
- otype for input (open drain or push pull)

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@st.com>