pnpbios: convert to use the kthread API

This patches modifies the pnpbios kernel thread to start with ktrhead_run
not kernel_thread and deamonize.  Doing this makes the code a little
simpler and easier to maintain.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Adam Belay <ambx1@neo.rr.com>
Cc: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>