tests: drivers: spi loopback test application for dma on stm32
tests: drivers: spi loopback test application for dma on stm32

This changes the spi_loopback test application to use the DMA transfer.
In case of DMA, some testcases are useless.
It requires the MOSI to be connected to the MISO of the SPI1.

Signed-off-by: Francois Ramu <b83adc7f8a23ee911a37fcb61c4033581aae0b7a@st.com>

finikorg/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,Vudentz/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,nashif/zephyr,Vudentz/zephyr,Vudentz/zephyr,finikorg/zephyr,galak/zephyr,Vudentz/zephyr,finikorg/zephyr,nashif/zephyr,nashif/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,galak/zephyr,nashif/zephyr,Vudentz/zephyr,Vudentz/zephyr,galak/zephyr