sfc: Fix transposed ptp_{under, over}size_sync_windows statistics

Somehow I transposed these two while bringing the original statistics
support upstream.

Fixes: 99691c4ac112 ('sfc: Add PTP counters to ethtool stats')
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: Shradha Shah <sshah@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/sfc/ptp.c

@@ -753,9 +753,9 @@ efx_ptp_process_times(struct efx_nic *efx, MCDI_DECLARE_STRUCT_PTR(synch_buf),
 		if (window < SYNCHRONISATION_GRANULARITY_NS) {
 			++ptp->invalid_sync_windows;
 		} else if (corrected >= MAX_SYNCHRONISATION_NS) {
-			++ptp->undersize_sync_windows;
-		} else if (corrected < ptp->min_synchronisation_ns) {
 			++ptp->oversize_sync_windows;
+		} else if (corrected < ptp->min_synchronisation_ns) {
+			++ptp->undersize_sync_windows;
 		} else {
 			ngood++;
 			last_good = i;