[clang-tidy] Concatenate nested namespaces (2/7: components d-h) (#16295)

esphome/components/display/display_buffer.cpp

@@ -5,8 +5,7 @@
 #include "esphome/core/application.h"
 #include "esphome/core/log.h"
 
-namespace esphome {
-namespace display {
+namespace esphome::display {
 
 static const char *const TAG = "display";
 
@@ -68,5 +67,4 @@ void HOT DisplayBuffer::draw_pixel_at(int x, int y, Color color) {
   App.feed_wdt();
 }
 
-}  // namespace display
-}  // namespace esphome
+}  // namespace esphome::display