feat(ff-a): add managed exit field in the manifest

Moving setting to enable/disable managed exit support from messaging
method field to a separate field in partition manifest. As of DEN0077A
FF-A v1.1 Beta0 section 5.2, managed exit support is moved out of
messaging-method field and is described in a separate field.

Signed-off-by: Maksims Svecovs <maksims.svecovs@arm.com>
Change-Id: I87506d7213b88d5a18073bea7357c381605d8b33
diff --git a/src/arch/fake/hypervisor/ffa.c b/src/arch/fake/hypervisor/ffa.c
index 5cf3d28..288b256 100644
--- a/src/arch/fake/hypervisor/ffa.c
+++ b/src/arch/fake/hypervisor/ffa.c
@@ -70,3 +70,9 @@
 	(void)target;
 	return 0;
 }
+
+bool plat_ffa_vm_managed_exit_supported(struct vm *vm)
+{
+	(void)vm;
+	return false;
+}