tests: spi: spi loopback test running on the stm32f767zi nucleo

Add support of the tests/drivers/spi/spi_loopabck
with dma (V1).
Connect MISO pin (D12) to MOSI (D11) pin on the board
to pass the test.

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