panasonic-laptop: Handle errors properly if they happen

acpi_pcc_retrieve_biosdata() returns success instead of error if
HKEY.SINF is invalid. Fix this.

Furthermore, if acpi_pcc_retrieve_biosdata() returns an error
during device addition, initialization is properly reverted but value
0 is returned, which means success. This would cause a crash when
later using or removing the device, so fix this too.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Cc: Harald Welte <laforge@gnumonks.org>
Cc: Bruno Premont <bonbons@linux-vserver.org>
Signed-off-by: Matthew Garrett <mjg@redhat.com>