boards: litex_vexriscv: Enable LiteX SPI driver

This commit enables LiteX SPI driver for litex_vexriscv board.

Signed-off-by: Daniel Craviee <dcraviee@internships.antmicro.com>
Signed-off-by: Mateusz Holenko <mholenko@antmicro.com>
4 files changed