ACPI / einj: Make error paths more talkative

It is absolutely unfriendly when one sees this:

  # modprobe einj
  modprobe: ERROR: could not insert 'einj': No such device

without anything in dmesg to tell one why the load failed.

Beef up the error handling of the init function to be more user-friendly
when the load fails.

Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>