gpio: stmfx: move function to prepare new ops introduction

Move the functions stmfx_pinctrl_set_pupd and stmfx_pinctrl_set_type;
they can be used by the new ops get_dir_flags and set_dir_flags introduced
by next patch.

No functional change.

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