benchmark: Fix NPD in Encode::deInitCodec()

In some cases where initCodec() fails, deInitCodec() should not
call AMediaCodec_stop() as mCodec is NULL.

Bug: 147158050
Test: poc in bug

Change-Id: I5dc1bf1fed8fe086e16a9f07e1289980333b8a12
diff --git a/media/tests/benchmark/src/native/encoder/Encoder.cpp b/media/tests/benchmark/src/native/encoder/Encoder.cpp
index f119cf3..8dc7cc6 100644
--- a/media/tests/benchmark/src/native/encoder/Encoder.cpp
+++ b/media/tests/benchmark/src/native/encoder/Encoder.cpp
@@ -159,6 +159,7 @@
         AMediaFormat_delete(mFormat);
         mFormat = nullptr;
     }
+    if (!mCodec) return;
     AMediaCodec_stop(mCodec);
     AMediaCodec_delete(mCodec);
     int64_t eTime = mStats->getCurTime();