fallback from each programmer's paged_load() or paged_write()
method, respectively. The return value needs to be checked for
being greater or equal than 0 rather equal to 0 in order to
assume the operation has been successful.
Fixes bug #18489: avrdude is too slow (20 byte/s)
git-svn-id: svn://svn.savannah.nongnu.org/avrdude/trunk@695 81a1dc3b-b13d-400b-aceb-764788c761c2