usb: f_mass_storage: Make use of the helper macro kthread_run()

Replace kthread_create/wake_up_process() with kthread_run()
to simplify the code.

Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Hongbo Li <lihongbo22@huawei.com>
Link: https://lore.kernel.org/r/20240903014249.3098082-1-lihongbo22@huawei.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>