RDMA/mlx5: Refactor get flow table function

_get_flow_table() requires the entire matcher being passed
while all it needs is the priority and namespace type.
Pass the priority and namespace type directly instead.

Link: https://lore.kernel.org/all/20220703205407.110890-5-saeed@kernel.org/
Signed-off-by: Mark Bloch <mbloch@nvidia.com>
Reviewed-by: Maor Gottlieb <maorg@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>