ACPI / idle: small formatting fixes

A quick cleanup with scripts/checkpatch.pl -f <file>.

Signed-off-by: Nick Desaulniers <nick.desaulniers@gmail.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>