pnp: add pnp_build_option() to the API

The subsequent AD181x quirk patch would like this as part of the API.
pnp_register_dependent_option() adds to the same dependent chain the quirk is
walking which is fairly unclean.  This enables a private option chain build
which it can then just add onto the end when done.

Signed-off-by: Rene Herman <rene.herman@gmail.com>
Tested-by: Uwe Bugla <uwe.bugla@gmx.de>
Acked-by: Uwe Bugla <uwe.bugla@gmx.de>
Acked-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Len Brown <len.brown@intel.com
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>