rapidio: add mport char device driver

Add mport character device driver to provide user space interface to
basic RapidIO subsystem operations.

See included Documentation/rapidio/mport_cdev.txt for more details.

[akpm@linux-foundation.org: fix printk warning on i386]
[dan.carpenter@oracle.com: mport_cdev: fix some error codes]
Signed-off-by: Alexandre Bounine <alexandre.bounine@idt.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Tested-by: Barry Wood <barry.wood@idt.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Aurelien Jacquiot <a-jacquiot@ti.com>
Cc: Andre van Herk <andre.van.herk@prodrive-technologies.com>
Cc: Barry Wood <barry.wood@idt.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>