pinctrl: st: Convert to use devm_ioremap_resource

devm_request_and_ioremap is deprecated. Use devm_ioremap_resource
instead.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Acked-by: Srinivas Kandagatla <srinivas.kandagatla@st.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>