drivers/powerpc: Replace _ALIGN_UP() by ALIGN()

_ALIGN_UP() is specific to powerpc
ALIGN() is generic and does the same

Replace _ALIGN_UP() by ALIGN()

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/a5945463f86c984151962a475a3ee56a2893e85d.1587407777.git.christophe.leroy@c-s.fr