DPE: Test: Fix const correctness and redefinition warning

Some define and macro get redefined if dpe_test_private.h
and dpe_context_mngr.h is included in the same file.

Change-Id: Idc03774dd5204c5661d5cad5de84562c2c82d26f
Signed-off-by: Tamas Ban <tamas.ban@arm.com>
1 file changed