[ Upstream commit 3144533bf667c8e53bb20656b78295960073e57b ]

The dlid assignment made by looking into the u_ucast_dlid array does not
do an explicit check for the size of the array. The code path to arrive at
def_port, the index value is long and complicated so its best to just have
an explicit check here.
Signed-off-by: NDennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: NJason Gunthorpe <jgg@mellanox.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>