[PATCH] natsemi: NAPI and a bugfix

This patch converts the natsemi driver to use NAPI.  It was originally
based on one written by Harald Welte, though it has since been modified
quite a bit, most extensively in order to remove the ability to disable
NAPI since none of the other drivers seem to provide that functionality
any more.

Signed-off-by: Mark Brown <broonie@sirena.org.uk>
Signed-off-by: Jeff Garzik <jeff@garzik.org>