fate: remove unnecessary reference file for fate-encryption-info

Signed-off-by: James Almer <jamrial@gmail.com>

tests/fate/libavutil.mak

@@ -73,6 +73,7 @@ fate-dict: CMD = run libavutil/tests/dict
 FATE_LIBAVUTIL += fate-encryption-info
 fate-encryption-info: libavutil/tests/encryption_info$(EXESUF)
 fate-encryption-info: CMD = run libavutil/tests/encryption_info
+fate-encryption-info: CMP = null
 
 FATE_LIBAVUTIL += fate-eval
 fate-eval: libavutil/tests/eval$(EXESUF)