uio: documentation fixups

The 'name' attribute of struct uio_mem wasn't documented, and the note
about 'kobj' is stale and needs to be changed to 'map'.

Signed-off-by: Geoff Thorpe <geoff@geoffthorpe.net>
Signed-off-by: "Hans J. Koch" <hjk@hansjkoch.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>