ice: fold ice_ptp_read_time into ice_ptp_gettimex64

This is a cleanup. It is unnecessary to have this function just to call
another function.

Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
Reviewed-by: Sai Krishna <saikrishnag@marvell.com>
Tested-by: Pucha Himasekhar Reddy <himasekharx.reddy.pucha@intel.com> (A Contingent worker at Intel)
Reviewed-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>