ptp: idt82p33: Add PTP_CLK_REQ_EXTTS support

82P33 family of chips can trigger TOD read/write by external
signal from one of the IN12/13/14 pins, which are set user
space programs by calling PTP_PIN_SETFUNC through ptp_ioctl

Signed-off-by: Min Li <min.li.xe@renesas.com>
Signed-off-by: David S. Miller <davem@davemloft.net>