Fix potential integer overflow in MPEG4Extractor

Test: build
Bug: 111792351
Change-Id: Ib21ce33fb6c473c217f1f2a35e2ce1c81256f22f
diff --git a/media/extractors/mp4/MPEG4Extractor.cpp b/media/extractors/mp4/MPEG4Extractor.cpp
index 0441359..262852f 100644
--- a/media/extractors/mp4/MPEG4Extractor.cpp
+++ b/media/extractors/mp4/MPEG4Extractor.cpp
@@ -5142,7 +5142,7 @@
         sampleCtsOffset = 0;
     }
 
-    if (size < (off64_t)(sampleCount * bytesPerSample)) {
+    if (size < (off64_t)sampleCount * bytesPerSample) {
         return -EINVAL;
     }