wait_for_initramfs warning from kernel_init_freeable()

From: Heiner Kallweit
Date: Thu Apr 29 2021 - 02:46:43 EST

Since 97f8172f9a98 ("init/initramfs.c: do unpacking asynchronously") I get
the following warning early in the boot process from umh:
"wait_for_initramfs() called before rootfs_initcalls"
Some debugging lead me to the following call chain:

-> do_basic_setup()
-> driver_init()
-> platform_bus_init()
-> bus_register()
-> kset_register()
-> kobject_uvent()