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

In order to clean powerpc's asm/prom.h 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 and 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: NChristophe Leroy <christophe.leroy@csgroup.eu>
Link: https://lore.kernel.org/r/09a13d592d628de95d30943e59b2170af5b48110.1651663857.git.christophe.leroy@csgroup.euSigned-off-by: NJakub Kicinski <kuba@kernel.org>