nfc: s3fwrn5: constify s3fwrn5_phy_ops structures

The s3fwrn5_phy_ops structure is never modified, so declare it as const.

Done with the help of Coccinelle.

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Acked-by: Robert Baldyga <r.baldyga@samsung.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>