ACPI / PM: Consolidate suspend-specific and hibernate-specific code

Move some suspend-specific and hibernate-specific code from
acpi_sleep_init() into separate functions to get rid of explicit
#ifdefs in acpi_sleep_init().  Use pr_info() to start and pr_cont()
to continue printing the supported ACPI sleep states line.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>