RDMA/mlx5: Fix flow steering egress flow

The commit mentioned in Fixes line removed the function that was
called to check validity of esp_aes_gcm attribute. Sadly, that
is_valid_esp_aes_gcm() returned success even for specs without
esp_aes_gcm at all.

So the right fix will be to remove whole if () and such fix
the following error observed in smatch too.

   drivers/infiniband/hw/mlx5/fs.c:1126 _create_flow_rule()
   warn: duplicate check 'is_egress' (previous on line 1098)

Fixes: de8bdb47

 ("RDMA/mlx5: Drop crypto flow steering API")
Link: https://lore.kernel.org/r/11b31c1f85bc8c8add385529aa3f307c3b383a11.1649842371.git.leonro@nvidia.com
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>