stm32mp1: add compilation flags for boot devices

Adds compilation flags to specify which drivers will be
embedded in the generated firmware.

Change-Id: Ie9decc89c3f26cf17e7148a3a4cf337fd35940f7
Signed-off-by: Nicolas Le Bayon <nicolas.le.bayon@st.com>
Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
2 files changed