boards: st: stm32g0xx nucleo fix morpho connector definition

On the nucleo_g071rb , nucleo_g070rb and nucleo_g0b1re boards,
the CN7 MORPHO_L_9 to 11 pin are not correctly defined
in the st_morpho_connector.dtsi. This PR is fixing this.

Signed-off-by: Francois Ramu <francois.ramu@st.com>