Fix a memory leak in the jpegdecode app (#180)

samples/jpegDecode/jpegdecode.cpp

@@ -191,7 +191,7 @@ int main(int argc, char **argv) {
         }
     }
 
-    for (int i = 0; i < num_channels; i++) {
+    for (int i = 0; i < ROCJPEG_MAX_COMPONENT; i++) {
         if (output_image.channel[i] != nullptr) {
             CHECK_HIP(hipFree((void *)output_image.channel[i]));
             output_image.channel[i] = nullptr;