ptp: idt82p33: Make two variables static

Fix sparse warnings:

drivers/ptp/ptp_idt82p33.c:26:5: warning: symbol 'sync_tod_timeout' was not declared. Should it be static?
drivers/ptp/ptp_idt82p33.c:31:5: warning: symbol 'phase_snap_threshold' was not declared. Should it be static?

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>