x86/acpi: Switch to pr_xxx log functions

Switching to pr_debug et al has two benefits:
- We don't have to add PREFIX to each log statement
- Debug output is suppressed except DEBUG is defined or dynamic
  debugging is enabled for the respective code piece.

In addition ensure that longer messages aren't split to multiple lines
in source code, checkpatch complains otherwise.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>