powerpc's asm/prom.h brings some headers that it doesn't
need itself.

In order to clean it up in a further step, first clean all
files that include asm/prom.h

Some files don't need asm/prom.h at all. For those ones,
just remove inclusion of asm/prom.h

Some files don't need any of the items provided by asm/prom.h,
but need some of the headers included by asm/prom.h. For those
ones, add the needed headers that are brought by asm/prom.h at
the moment, then remove asm/prom.h

Some files really need asm/prom.h but also need some of the
headers included by asm/prom.h. For those one, leave asm/prom.h
but also add the needed headers so that they can be removed
from asm/prom.h in a later step.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Link: https://lore.kernel.org/r/295e87a3094a92784657f7060fb0927e762a2e3c.1650011506.git.christophe.leroy@csgroup.euSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>