aoe: jumbo frame support 1 of 2

Add support for jumbo ethernet frames.
(This patch depends on patch 7 to follow.)

Signed-off-by: "Ed L. Cashin" <ecashin@coraid.com>
Acked-by: Alan Cox <alan@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>