tests: drivers: spi loopback testing on the nucleo_h743/h753 boards

Reduce the spi1 clock freq to pass the testcase on the nucleo
_h753zi or nucleo_h743zi boards
Connect D11 & D12 pins on the board to pass the test

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