DM: Add rename_device()
DM: Add rename_device()

Unfortunately I can't use a const expr when making an array so I had to
add a const for the size of the ioctl struct.

Signed-off-by: Andy Grover <b7d524d2f5cc5aebadb6b92b08d3ab26911cde33@redhat.com>

agrover/melvin