egl/wayland: fix formatting and add trailing comma

Commit 659bace0 ("egl: add a few trailing commas") added a few trailing commas to the last item in a struct to avoid that commit e85983d7 ("egl: re-format using clang-format") moves the closing brace into the previous line.

The wl_callback_listener was missing the comma and the brace was moved to the previous line, which makes it harder to read the code.

Add the comma and fix the formatting.