net/mlx5: DR, Check force-loopback RC QP capability independently from RoCE

SW Steering uses RC QP for writing STEs to ICM. This writingis done in LB
(loopback), and FL (force-loopback) QP is preferred for performance. FL is
available when RoCE is enabled or disabled based on RoCE caps.
This patch adds reading of FL capability from HCA caps in addition to the
existing reading from RoCE caps, thus fixing the case where we didn't
have loopback enabled when RoCE was disabled.

Fixes: 7304d603 ("net/mlx5: DR, Add support for force-loopback QP")
Signed-off-by: Itamar Gozlan <igozlan@nvidia.com>
Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>