ACPI suspend: Fix compilation warnings in drivers/acpi/sleep.c

Fix two compilation warnings in drivers/acpi/sleep.c, one triggered
by unsetting CONFIG_SUSPEND and the other triggered by unsetting
CONFIG_HIBERNATION, by moving some code under the appropriate
#ifdefs .

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Len Brown <len.brown@intel.com>