ETHER_MAX_LEN_JUMBO

[Garrett Wollman]

In <net/ethernet.h>, the constant ETHER_MAX_LEN_JUMBO is set to 9018.
According to svn, this was added by sam back in 2002, and now seems a
bit low.  Our maximum MTU at work has always been 9120 (implying 9138
for ETHER_MAX_LEN_JUMBO), and we have hardware in production now that
defaults to 12000.  The ixgbe driver doesn't use this constant, bu
the cxgbe driver does.  Does anyone know a reason I should *not*
increase it to a more reasonable level?  (9216 would be my choice if
we wanted to stick with values in the 9k range.)

-GAWollman