Driver core: fix SYSF_DEPRECATED breakage for nested classdevs

We should only reparent to a class former class devices that
form the base of class hierarchy. Nested devices should still
grow from their real parents.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Tested-by: Andrey Borzenkov <arvidjaar@mail.ru>
Tested-by: Anssi Hannula <anssi.hannula@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>