pinctrl: stmfx: update pinconf settings

According to the following tab (coming from STMFX datasheet), updates
have to done in stmfx_pinconf_set function:

-"type" has to be set when "bias" is configured as "pull-up or pull-down"
-PIN_CONFIG_DRIVE_PUSH_PULL should only be used when gpio is configured as
 output. There is so no need to check direction.

DIR | TYPE | PUPD | MFX GPIO configuration
----|------|------|---------------------------------------------------
1   | 1    | 1    | OUTPUT open drain with internal pull-up resistor
----|------|------|---------------------------------------------------
1   | 1    | 0    | OUTPUT open drain with internal pull-down resistor
----|------|------|---------------------------------------------------
1   | 0    | 0/1  | OUTPUT push pull no pull
----|------|------|---------------------------------------------------
0   | 1    | 1    | INPUT with internal pull-up resistor
----|------|------|---------------------------------------------------
0   | 1    | 0    | INPUT with internal pull-down resistor
----|------|------|---------------------------------------------------
0   | 0    | 1    | INPUT floating
----|------|------|---------------------------------------------------
0   | 0    | 0    | analog (GPIO not used, default setting)

Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>
Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Link: https://lore.kernel.org/r/1564053416-32192-1-git-send-email-amelie.delaunay@st.com


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>