9p: disallow RDMA if RDMA CM isn't available

If INET=y and INFINIBAND=y, but IPV6=m then INFINIBAND_ADDR_TRANS is set
to n and the RDMA CM functions rdma_connect() et al are not built.
However, the current config dependencies allow NET_9P_RDMA to be selected
in this, which leads to a build failure.  Fix this by adding a dependency
on INFINIBAND_ADDR_TRANS to disallow NET_9P_RDMA in this case.

Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Tested-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>