nfc: s3fwrn5: constify nci_ops

s3fwrn5 driver modifies static struct nci_ops only to set prop_ops.
Since prop_ops is build time constant with known size, it can be made
const.  This allows to removeo the function setting the prop_ops -
s3fwrn5_nci_get_prop_ops().

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>