Remove qemu_run_machine_init_done_notifiers() since no implementation
and user.

Fixes: f66dc873 ("vl: move all generic initialization out of vl.c")
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20220104024136.1433545-1-xiaoyao.li@intel.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>