[PATCH] 3c59x: don't enable scatter/gather w/o checksum support

It is not valid to enable scatter/gather without hardware checksum support
of some kind. (akpm: applies only to the old boomerang cards).

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>