tests: drivers: spi loopback on nucleo_f411 board

This configures the nucleo_f411re board for testing the SPI loopback
with DMA V1 transfer. DMA instance 2 is used.
This test requires pin SPI_A_MISO (D12) to be connected
to pin SPI_A_MOSI (D11) on the nucleo_wb55rg boardtest dma_V1

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