Partitions: Fix minor header include issues

tfm_veneers.h is used by Library Mode only.
This patch fixes some include issue where tfm_veneer.h is included
for both Mode.

Change-Id: I87830222e7fec0098ed77f43006639dba3937a44
Signed-off-by: Kevin Peng <kevin.peng@arm.com>
5 files changed