ACPI: sleep: Unify the message printing

Intoduce pr_fmt() and use pr_*() macros to replace printk(), also
remove all the PREFIX for pr_*() calls to generate a unified format
string for prefix.

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