driver for Silan SC92031 netdev

This is a driver for the Silan SC92031/Rsltek 8139D NIC chip.

This chip is found on at least one counterfeit Encore ENL832-TX-RENT NIC
[1], which came with a mini-CD with the 2.4 driver.  A slightly older
version of the driver was found at [2].  The main difference between them
is that the newer one has a small bugfix in the RX path, a lot of
gratuitous renaming of functions, all the printable strings changed to show
as a "Rsltek 8139D" [sic], and a PCI ID of 8139 instead of 2031.  The
driver on this patch is a rewrite of the vendor drivers (based mostly on
the older one).

Changes from the previous patch sent to netdev:
- Use MMIO instead of PIO
- Changed TX bounce buffers allocation
- Use skb_copy_and_csum_dev
- Several small bug fixes
- Tested for more than just a few minutes each time

[1] See http://www.encore-usa.com/faq.php under ENL832-TX-RENT for more
    information
[2] Look for SL_LINUX.ZIP (which is really a .tar.gz) at
    http://broadbandforum.in/dataone_Intex_LAN_cardlinux-t4207-s15.html


[3] To compile on 2.6.17, simply add back the last argument to the
    interrupt handler in two places, and copy the boolean declarations
    from 2.6.19

[akpm@osdl.org: build fixes]
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>