net: aquantia: make two symbols be static

When using ARCH=mips CROSS_COMPILE=mips-linux-gnu-
to build drivers/net/ethernet/aquantia/atlantic/aq_ptp.o
and drivers/net/ethernet/aquantia/atlantic/hw_atl/hw_atl_b0.o,
below errors can be seen:
drivers/net/ethernet/aquantia/atlantic/aq_ptp.c:1378:6:
warning: symbol 'aq_ptp_poll_sync_work_cb' was not declared.
Should it be static?

drivers/net/ethernet/aquantia/atlantic/hw_atl/hw_atl_b0.c:1155:5:
warning: symbol 'hw_atl_b0_ts_to_sys_clock' was not declared.
Should it be static?

This patch to make aq_ptp_poll_sync_work_cb and hw_atl_b0_ts_to_sys_clock
be static to fix these warnings.

Fixes: 9c477032 ("net: aquantia: add support for PIN funcs")
Signed-off-by: Mao Wenan <maowenan@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>