platform/x86: fujitsu-laptop: rework debugging

Using a dedicated Kconfig option for enabling debugging means the user
may be forced to recompile their kernel in order to gather debugging
information, which is inconvenient.  Replace custom debugging
infrastructure with standard logging functions, taking advantage of
dynamic debug.  Replace a pr_info() call inside an ACPI callback with an
acpi_handle_info() call.

The following mapping was used:

  - FUJLAPTOP_DBG_ERROR -> acpi_handle_err()
  - FUJLAPTOP_DBG_WARN  -> acpi_handle_info() / dev_info()
  - FUJLAPTOP_DBG_INFO  -> acpi_handle_debug()
  - FUJLAPTOP_DBG_TRACE -> acpi_handle_debug() / dev_dbg()

This means that some events which used to only be logged when the user
explicitly requested it will now be logged by default:

  - ACPI method evaluation errors,
  - unknown ACPI notification codes,
  - unknown hotkey scancodes.

The first type of events should happen rarely, if ever at all.  The rest
is interesting from driver development perspective as their presence in
the logs will mean the driver is unaware of certain events, handling of
which should be implemented.

Signed-off-by: Michał Kępień <kernel@kempniu.pl>
Reviewed-by: Jonathan Woithe <jwoithe@just42.net>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>