arm: stm32mp: add defconfig for trusted boot with FIP

arm: stm32mp: add defconfig for trusted boot with FIP

Add TF-A FIP support for trusted boot on STM32MP15x,
when STM32MP15x_STM32IMAGE is not activated.

With FIP support the SSBL partition is named "fip" and its size is 4MB,
so the ENV partition name in device tree  (for SD card or eMMC)
or offset in defconfig (CONFIG_ENV_OFFSET / CONFIG_ENV_OFFSET_REDUND)
need to be modified.

With FIP the TEE MTD partitions are removed because the OP-TEE binray are
included in the FIP containers.

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