power management: implement pm_ops.valid for everybody

Almost all users of pm_ops only support mem sleep, don't check in .valid and
don't reject any others in .prepare so users can be confused if they check
/sys/power/state, especially when new states are added (these would then
result in s-t-r although they're supposed to be something different).

This patch implements a generic pm_valid_only_mem function that is then
exported for users and puts it to use in almost all existing pm_ops.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Cc: David Brownell <david-b@pacbell.net>
Acked-by: Pavel Machek <pavel@ucw.cz>
Cc: linux-pm@lists.linux-foundation.org
Cc: Len Brown <lenb@kernel.org>
Acked-by: Russell King <rmk@arm.linux.org.uk>
Cc: Greg KH <greg@kroah.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/arm/mach-omap1/pm.c b/arch/arm/mach-omap1/pm.c
index 4248117..0383ab3 100644
--- a/arch/arm/mach-omap1/pm.c
+++ b/arch/arm/mach-omap1/pm.c
@@ -701,6 +701,7 @@
 	.prepare	= omap_pm_prepare,
 	.enter		= omap_pm_enter,
 	.finish		= omap_pm_finish,
+	.valid		= pm_valid_only_mem,
 };
 
 static int __init omap_pm_init(void)