RDMA/qedr: Remove enumerated type qed_roce_ll2_tx_dest

Clang warns when one enumerated type is explicitly converted to another.

drivers/infiniband/hw/qedr/qedr_roce_cm.c:198:28: warning: implicit
conversion from enumeration type 'enum qed_roce_ll2_tx_dest' to
different enumeration type 'enum qed_ll2_tx_dest' [-Wenum-conversion]
        ll2_tx_pkt.tx_dest = pkt->tx_dest;
                           ~ ~~~~~^~~~~~~
1 warning generated.

Turns out that QED_ROCE_LL2_TX_DEST_NW and QED_ROCE_LL2_TX_DEST_LB are
only used once in the whole tree and QED_ROCE_LL2_TX_DEST_MAX is used
nowhere. Remove them and use the equivalent values from qed_ll2_tx_dest
in their place.

Reported-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Michal Kalderon <michal.kalderon@cavium.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>