net/mlx5: Reliably return TLS device capabilities

The capabilities returned from the FW are independent to the compiled
kernel and traditionally rely on the relevant CAPs bit only.

The mlx5_accel_is_ktls_*() functions are compiled out if CONFIG_MLX5_TLS
is not set, which "hides" from the user the information that TLS can be
enabled on this device.

Link: https://lore.kernel.org/r/a333ce541fb9497d04126b11c4a0052f9807d141.1649073691.git.leonro@nvidia.com


Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>