DCT QPs have separate creation flow and can be easily extracted
from configure_responder_scat_cqe(), this makes both updated
functions more clear.

Link: https://lore.kernel.org/r/20200427154636.381474-9-leon@kernel.orgReviewed-by: NMaor Gottlieb <maorg@mellanox.com>
Signed-off-by: NLeon Romanovsky <leonro@mellanox.com>
Signed-off-by: NJason Gunthorpe <jgg@mellanox.com>