ACPI / tables: Replace printk with pr_*

This patch just does some cleanup to replace printk with pr_*,
and introduces pr_fmt() to remove all PREFIXs in tables.c,
no functional change.

Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>