drm_hwcomposer: CI: Upgrade to clang-13 && clang-tidy-13

+ address new clang-tidy findings.

Signed-off-by: Roman Stratiienko <roman.o.stratiienko@globallogic.com>
diff --git a/hwc2_device/HwcDisplay.cpp b/hwc2_device/HwcDisplay.cpp
index 9055a9a..9f7bcd8 100644
--- a/hwc2_device/HwcDisplay.cpp
+++ b/hwc2_device/HwcDisplay.cpp
@@ -505,7 +505,7 @@
  * https://cs.android.com/android/platform/superproject/+/android-11.0.0_r3:hardware/libhardware/include/hardware/hwcomposer2.h;l=1805
  */
 HWC2::Error HwcDisplay::PresentDisplay(int32_t *present_fence) {
-  HWC2::Error ret;
+  HWC2::Error ret{};
 
   ++total_stats_.total_frames_;