configs: stm32mp1: move SUPPORT_SPL in STM32MP15x

The SPL is only supported by STM32MP15x not by all the
SOC with STM32MP arch.
Only TFABOOT is supported in next products.

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