tcp: fix the missing avr32 SOF_TIMESTAMPING_OPT_STATS

The commit of SOF_TIMESTAMPING_OPT_STATS didn't include the
new header for avr32, causing build to break. The patch fixes it.

Fixes: 1c885808 ("tcp: SOF_TIMESTAMPING_OPT_STATS option for SO_TIMESTAMPING")
Reported-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>