With 32 bit compilation several of the fields become misaligned here.
Fixing this is an ABI break for 32 bit rxe and it is in well used
portions of the rxe ABI.

To handle this we bump the ABI version, as expected. However the user
space driver doesn't handle it properly today, so all existing user
space continues to work.

Updated userspace will start to require the necessary kernel version.

We don't expect there to be any 32 bit users of rxe. Most likely cases,
such as ARM 32 already generally don't work because rxe does not handle
the CPU cache properly on its shared with userspace pages.
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>