ARM: Do 15e0d9e37c (ARM: pm: let platforms select cpu_suspend support) properly

commit b6c7aabd923a17af993c5a5d5d7995f0b27c000a upstream.

Let's do the changes properly and fix the same problem everywhere, not
just for one case.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
[bwh: Backported to 3.2: mohawk doesn't support suspend at all]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>