orangefs: simplify the read/write path.

Removed vestigial readx/writex code.

replaced filesystem specific file_operations read and write with
their generic counterparts who turn right around and call the
filesystem specific aio_read and aio_write with single segments.

updated Makefile so I could see a difference in uname -a

Signed-off-by: Mike Marshall <hubcap@omnibond.com>