refactor(ff-a): init

Move `plat_ffa_init` and `plat_ffa_log_init` to new `init.c` file.

Change-Id: I65484c6d5cd868de01c5bb8fb3edd103a0d61262
Signed-off-by: Karl Meakin <karl.meakin@arm.com>
diff --git a/src/init.c b/src/init.c
index 957392d..e4362bf 100644
--- a/src/init.c
+++ b/src/init.c
@@ -19,6 +19,7 @@
 #include "hf/dlog.h"
 #include "hf/fdt_handler.h"
 #include "hf/ffa.h"
+#include "hf/ffa/init.h"
 #include "hf/load.h"
 #include "hf/manifest.h"
 #include "hf/mm.h"