feat(stm32mp1): add the platform specific build for tools

Add cert_create and fiptool specific files to add the platform
addons to the generic tools.

Change-Id: Ifa600241cdf32b495cc65edccddab47c3796b77d
Signed-off-by: Lionel Debieve <lionel.debieve@foss.st.com>
2 files changed