smb: smbdirect: introduce smbdirect_connect[_sync]()

smb: smbdirect: introduce smbdirect_connect[_sync]()

This implements a fully async connect logic over
all rdma related operations: rdma_resolve_addr,
rdma_resolve_route and rdma_connect_locked
until we reach RDMA_CM_EVENT_ESTABLISHED,
followed by the smbdirect negotiation request/response
handling until we reach SMBDIRECT_SOCKET_CONNECTED.

smbdirect_connect_sync() is just a useful wrapper
around the async logic calling smbdirect_connect()
followed by smbdirect_connection_wait_for_connected(),
which only waits for SMBDIRECT_SOCKET_CONNECTED or
an error.

Cc: Steve French <smfrench@gmail.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Long Li <longli@microsoft.com>
Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>