netxen: sanitize variable names

o remove max_ prefix from ring sizes, since they don't really
  represent max possible sizes.
o cleanup naming of rx ring types (normal, jumbo, lro).
o simplify logic to choose rx ring size, gig ports get half
  rx ring of 10 gig ports.

Signed-off-by: Dhananjay Phadke <dhananjay@netxen.com>
Signed-off-by: David S. Miller <davem@davemloft.net>