[nvo] Remove the non-volatile options fragment list

[nvo] Remove the non-volatile options fragment list

Since its implementation several years ago, no driver has used a
fragment list containing more than a single fragment.  Simplify the
NVO core and the drivers that use it by removing the whole concept of
the fragment list, and using a simple (address,length) pair instead.

Signed-off-by: Michael Brown <mcb30@ipxe.org>