RDMA/erdma: Add address handle implementation

RDMA/erdma: Add address handle implementation

The address handle contains the necessary information to transmit
messages to a remote peer in the RoCEv2 protocol. This commit
implements the erdma_create_ah(), erdma_destroy_ah(), and
erdma_query_ah() interfaces, which are used to create, destroy,
and query an address handle, respectively.

Signed-off-by: Boshi Yu <boshiyu@linux.alibaba.com>
Link: https://patch.msgid.link/20241211020930.68833-5-boshiyu@linux.alibaba.com
Reviewed-by: Cheng Xu <chengyou@linux.alibaba.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>