RDMA/core: Fix broadcast address falsely detected as local

RDMA/core: Fix broadcast address falsely detected as local

When rdma_resolve_addr() is invoked with a broadcast destination on an
IPoIB interface, is_dst_local() inspects the resolved route and
incorrectly concludes that the address is local. As a result, the
resolution fails with -ENODEV.
The issue stems from using '&' to compare rt_type with RTN_LOCAL. The
RTN_* values form a sequential enum, not a bitmask (RTN_LOCAL=2,
RTN_BROADCAST=3). Thus, "rt_type & RTN_LOCAL" yields a non-zero result
for a broadcast route as well.

Replace '&' with '==' when comparing rt_type against RTN_LOCAL.

Link: https://patch.msgid.link/r/20260609-fix-rdma-resolve-addr-v1-1-449b8b4e6c09@nvidia.com
Cc: stable@vger.kernel.org
Fixes: c31e4038c97f ("RDMA/core: Use route entry flag to decide on loopback traffic")
Signed-off-by: Maher Sanalla <msanalla@nvidia.com>
Reviewed-by: Vlad Dumitrescu <vdumitrescu@nvidia.com>
Signed-off-by: Edward Srouji <edwards@nvidia.com>
Reviewed-by: Parav Pandit <parav@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>