net: hns: make function hns_gmac_wait_fifo_clean() static

net: hns: make function hns_gmac_wait_fifo_clean() static

BugLink: https://bugs.launchpad.net/bugs/1810457
Fixes the following sparse warning:

drivers/net/ethernet/hisilicon/hns/hns_dsaf_gmac.c:322:5: warning:
 symbol 'hns_gmac_wait_fifo_clean' was not declared. Should it be static?

Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 0a959e45846ad697c54f0d2bd71fa55bdd1a8a39)
Signed-off-by: dann frazier <dann.frazier@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>