camera: fix `-Wunused-variable` compiler warnings

Test: add `USE_CAMERA_V4L2_HAL := true` to
      hardware/libhardware/modules/camera/3_4/Android.mk and build
      mmm hardware/libhardware/modules/camera/3_4
Change-Id: I2755278b739db0bb746a78d0b66e1f644a44ff19
Signed-off-by: Sergii Piatakov <sergii.piatakov@globallogic.com>
diff --git a/modules/camera/3_4/request_tracker.cpp b/modules/camera/3_4/request_tracker.cpp
index d4cbe47..4168c3b 100644
--- a/modules/camera/3_4/request_tracker.cpp
+++ b/modules/camera/3_4/request_tracker.cpp
@@ -128,7 +128,6 @@
 
   // Check that each stream has space
   // (which implicitly checks if it is configured).
-  bool result = true;
   for (const auto stream : RequestStreams(request)) {
     if (StreamFull(stream)) {
       ALOGE("%s: Stream %p is full.", __func__, stream);