configs: stm32746g-eval: Add stm32746g-eval_spl_defconfig

Add stm32746g-eval_spl_defconfig for stm32746g evaluation board to
build SPL.

Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
2 files changed