ice/ptp: fix crosstimestamp reporting

Set use_nsecs=true as timestamp is reported in ns. Lack of this result
in smaller timestamp error window which cause error during phc2sys
execution on E825 NICs:
phc2sys[1768.256]: ioctl PTP_SYS_OFFSET_PRECISE: Invalid argument

This problem was introduced in the cited commit which omitted setting
use_nsecs to true when converting the ice driver to use
convert_base_to_cs().

Testing hints (ethX is PF netdev):
phc2sys -s ethX -c CLOCK_REALTIME  -O 37 -m
phc2sys[1769.256]: CLOCK_REALTIME phc offset -5 s0 freq      -0 delay    0

Fixes: d4bea54 ("ice/ptp: Remove convert_art_to_tsc()")
Signed-off-by: Anton Nadezhdin <[email protected]>
Reviewed-by: Aleksandr Loktionov <[email protected]>
Reviewed-by: Arkadiusz Kubalewski <[email protected]>
Tested-by: Rinitha S <[email protected]> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <[email protected]>

Author: anadezhd

drivers/net/ethernet/intel/ice/ice_ptp.c

@@ -2299,6 +2299,7 @@ static int ice_capture_crosststamp(ktime_t *device,
 	ts = ((u64)ts_hi << 32) | ts_lo;
 	system->cycles = ts;
 	system->cs_id = CSID_X86_ART;
+	system->use_nsecs = true;
 
 	/* Read Device source clock time */
 	ts_lo = rd32(hw, cfg->dev_time_l[tmr_idx]);