powerpc: fix build errors in stable tree

This is just the first chunk of commit
222f20f140623ef6033491d0103ee0875fe87d35 upstream.

to fix a build error in the powerpc tree due to other backports
happening (and this full patch not being backported).

Reported-by: Guenter Roeck <linux@roeck-us.net>
Reported-by: Yves-Alexis Perez <corsac@debian.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Yves-Alexis Perez <corsac@debian.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>