drm_hwcomposer: CI: Bump-up clang toolchain to v15

Address new clang-tidy findings, in most cases 'misc-const-correctness'
check was addressed by adding 'const' modifier, or in some cases changed
to 'auto' (where it's better for formatting).

Signed-off-by: Roman Stratiienko <r.stratiienko@gmail.com>
diff --git a/hwc2_device/HwcLayer.cpp b/hwc2_device/HwcLayer.cpp
index c278732..589a0a7 100644
--- a/hwc2_device/HwcLayer.cpp
+++ b/hwc2_device/HwcLayer.cpp
@@ -205,6 +205,11 @@
 void HwcLayer::PopulateLayerData(bool test) {
   ImportFb();
 
+  if (!layer_data_.bi) {
+    ALOGE("%s: Invalid state", __func__);
+    return;
+  }
+
   if (blend_mode_ != BufferBlendMode::kUndefined) {
     layer_data_.bi->blend_mode = blend_mode_;
   }
@@ -227,7 +232,7 @@
     return false;
   }
 
-  int seq = swchain_lookup_table_[unique_id];
+  auto seq = swchain_lookup_table_[unique_id];
 
   if (swchain_cache_.count(seq) == 0) {
     return false;
@@ -274,7 +279,7 @@
       return;
     }
 
-    int seq = swchain_lookup_table_[unique_id];
+    auto seq = swchain_lookup_table_[unique_id];
 
     if (swchain_cache_.count(seq) == 0) {
       swchain_cache_[seq] = {};