RDMA/erdma: Add the ABI definitions

Add erdma ABI definitions which will be shared between kernel and
userspace. This commit also fix compile issues reported by lkp.

Link: https://lore.kernel.org/r/20220727014927.76564-11-chengyou@linux.alibaba.com


Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Cheng Xu <chengyou@linux.alibaba.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>