RDMA/mlx5: Fix wrong free of blue flame register on error

If the allocation of the fast path blue flame register fails, the driver
should free the regular blue flame register allocated a statement above,
not the one that it just failed to allocate.

Fixes: 16c1975f

 ("IB/mlx5: Create profile infrastructure to add and remove stages")
Link: https://lore.kernel.org/r/20210113121703.559778-6-leon@kernel.org
Reported-by: Hans Petter Selasky <hanss@nvidia.com>
Signed-off-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>