rapidio/rionet: add capability to change MTU

These patches are the result of extensive collaboration within the
RapidIO.org Software Task Group between Texas Instruments, Freescale,
Prodrive Technologies, Nokia Networks, BAE and IDT.  Additional input
was received from other members of RapidIO.org.  The objective was to
create a character mode driver interface which exposes the capabilities
of RapidIO devices directly to applications, in a manner that allows the
numerous and varied RapidIO implementations to interoperate.

The Software Task Group has also developed fabric management, Remote
Memory Access, and sockets applications which make use of these
interfaces in user space.  Intensive testing with these applications
prompted the RapidIO subsystem updates provided within this set of
patches.

This patch (of 29):

Replace default Ethernet-specific routine by the custom one to allow
setting of larger MTU supported by RapidIO messaging (max RIO packet
size is 4096 bytes).

Signed-off-by: Aurelien Jacquiot <a-jacquiot@ti.com>
Signed-off-by: Alexandre Bounine <alexandre.bounine@idt.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Andre van Herk <andre.van.herk@prodrive-technologies.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>