fix(st): mark INCBIN-generated sections as SHF_ALLOC

This is the same as rk3399 patch[1], add "a" option for sections
added to create stm32 file (containing BL2 and its DTB) in order to
properly link with clang.
This is still working with GCC.

[1]: 279cad8ed3 fix(rk3399): mark INCBIN-generated sections as SHF_ALLOC

Signed-off-by: Yann Gautier <yann.gautier@st.com>
Change-Id: Id5db55580c9c156aa6bf616c7c09a9307bca85f9
2 files changed